Thiol-ene reaction

Last updated

In organosulfur chemistry, the thiol-ene reaction (also alkene hydrothiolation) is an organic reaction between a thiol (R−SH) and an alkene (R2C=CR2) to form a thioether (R−S−R'). This reaction was first reported in 1905, [1] but it gained prominence in the late 1990s and early 2000s for its feasibility and wide range of applications. [2] [3] This reaction is accepted as a click chemistry reaction given the reactions' high yield, stereoselectivity, high rate, and thermodynamic driving force.

Contents

Basic schematic of thiol-ene addition reaction Basic schematic of thiol-ene addition reaction.png
Basic schematic of thiol-ene addition reaction

The reaction results in an anti-Markovnikov addition of a thiol compound to an alkene. Given the stereoselectivity, high rate and yields, this synthetically useful reaction may underpin future applications in material and biomedical sciences. [2] [4]

Mechanisms

Radical addition

Thiol-ene additions are known to proceed through two mechanisms: free-radical additions and catalyzed Michael additions. Free-radical additions can be initiated by light, heat or radical initiators, which form a thiyl radical species. The radical then propagates with an ene functional group via an anti-Markovnikov addition to form a carbon-centered radical. A chain-transfer step removes a hydrogen radical from a thiol, which can subsequently participate in multiple propagation steps. [4]

Thiol-ene radical additions are advantageous for chemical synthesis because the step growth (propagation and chain-transfer steps) and chain growth (homopolymerization) processes can be effectively used to form homogeneous polymer networks. Photopolymerization is a useful radical-based reaction for applications within the nanotechnology, biomaterial, and material sciences, but these reactions are hindered by the inhibitory capabilities of oxygen. The thiol-ene radical addition combines the benefits of photopolymerization reactions with the aforementioned advantages of click chemistry reactions. This reaction is useful to the field of radical-based photopolymerization because it quantitatively and rapidly proceeds through a simple mechanism under ambient atmospheric conditions. [4] The carbon-centered radical can undergo chain-growth polymerization depending on the thiol and ene functional groups. This free-radical polymerization can be useful in the synthesis of uniform polymer networks. [5]

Michael addition

Thiol-ene reactions are known to proceed through a Michael addition pathway. These reactions are catalyzed by either a base or a nucleophile, resulting in a similar anti-Markovnikov addition product as the thiol-ene radical addition. [6]

Kinetics

Click chemistry reactions are known to be high efficiency and have fast reaction rates, yet there is considerable variability in the overall reaction rate depending on the functionality of the alkene. To better understand the kinetics of thiol-ene reactions, calculations and experiments of transition-state and reaction enthalpies were conducted for a number of alkenes and their radical intermediates. [5] [7] It was shown that the reactivity and structure of the alkene determines whether the reaction will follow a step-growth or chain-growth pathway. [5] It was also shown that the thiol-ene polymerization can be tuned by enhancing intermolecular interactions between the thiol and alkene functional groups. [7] A currently accepted trend is that electron-rich alkenes (such as vinyl ether or allyl ether) and norbornene are highly reactive compared to conjugated and electron-poor alkenes (butadiene and methoxyethene). In the case of norbornene and vinyl ether only step-growth is observed, no homopolymerization occurs after the formation of the carbon centered radical. [4]

Thiol-ene radical addition reaction rate relationship Thiol-ene radical addition reaction rate relationship.png
Thiol-ene radical addition reaction rate relationship

Due to the complex kinetics of this two-step cyclic reaction, the rate-determining step was difficult to delineate. Given that the rates of both steps must be equal, the concentration of the radical species is determined by the rate constant of the slower of the reaction steps. Thus the overall reaction rate (RP) can be modeled by the ratio of the propagation rate (kP) to the chain-transfer rate (kCT).The behavior of the reaction rate is outlined by the relationship below. In all cases the reaction is first order, when kP ≫ kCT [Eq. 1] the reaction rate is determined by the thiol concentration and the rate limiting step is chain-transfer, when kP ≪ kCT [Eq. 2] the reaction rate is determined by the alkene concentration and the rate limiting step is the propagation, and finally when kP ≈ kCT [Eq. 3] the reaction is half order with respect to both the alkene and thiol concentrations.

The functional groups on the thiol and alkene compounds can affect the reactivity of the radical species and their respective rate constants. The structure of the alkene determines whether the reaction will be propagation or chain-transfer limited, and therefore first order with respect to alkene or thiol concentration respectively. In the case of reactive alkenes, such as allyl ether, chain-transfer is the rate-limiting step, while in the case of less reactive alkenes, such as vinyl silazanes, propagation is the rate-limiting step. The thiol's hydrogen affinity also affects the rate-limiting step. Alkyl thiols have less abstractable protons and therefore the chain-transfer step has a lower reaction rate than the propagation step. [4]

Scheme of photoinitiated thiol-ene click reaction. Photoinitiated thiol-ene coupling reaction.gif
Scheme of photoinitiated thiol-ene click reaction.

Most time the quasi-first-order reaction yields a kinetic rate equation following the exponential decay function for the reactants and products.

[normalized thiol-ene product] =

where k is an effective rate constant and t is time.

However, when the radical generation becomes the rate-limiting step, an induction period is often observed at the early stage of the reaction, for example, for photoinitiated reaction under weak light condition. The kinetic curve deviates from the exponential decay function for a common first-order reaction by having a slow growth period. The kinetic model has to include the radical generation step to explain this induction period (right figure). The final expression has a Gaussian-like shape. [8]

[normalized thiol-ene product] =

where k is an effective rate constant and t is time.

Synthetically useful thiol-ene reactions

Initiation of cascade cyclization

The thiol-ene reaction (and analogous thiol-yne reaction) have extensively been used in generating reactive intermediates for the cyclization of unsaturated substrates. Radical hydrothiolation of an unsaturated functional group indirectly generates a carbon-centered radical, which can then cyclize intramolecularly onto alkenes, oxime ethers, isocyanides, cyano groups, and aromatic rings. [9] The use of thiyl radicals as initiators of cyclization has been employed in the synthesis of a number of natural products, including aplysins, [10] α-kainic acid, [11] asperparalines, [12] and alkaloids such as narciclasine and lycoricidine. [13]

The synthesis of kainic acid via thiyl radical-induced cyclization. Kainic acid synthesis.png
The synthesis of kainic acid via thiyl radical-induced cyclization.

Intramolecular thiol-ene reactions

Intramolecular thiol-ene reactions provide a means to create sulphur-containing heterocycles. The radical-initiated thiol-ene reaction has enabled the synthesis of four- to eight-membered rings, as well as macrocycles. While the radical thiol-ene reaction favors the anti-Markovnikov product, the regiochemistry of the cycloaddition depends on substituent effects and reaction conditions, which serve to direct the cyclization towards the thermodynamically or kinetically favored product respectively. This section examines intramolecular thiol-ene cyclization reactions, which yields a mixture of 5-exo and 6-endo products in order to facilitate a discussion of the factors, which may affect the regioselectivity of the intramolecular addition. This reaction has relevance for the synthesis of C-linked thiosugars. [14] Both the furanose and pyranose thiosugars can be prepared from the same thiyl radical precursor; 5-exo and 6-endo cyclizations of this precursor form the respective desired compound. The conditions under which these cyclization reactions occur follow Baldwin's rules for ring closure.

Thiosugar 5-exo and 6-endo cyclization Thiosugar 5-exo and 6-endo cyclization.png
Thiosugar 5-exo and 6-endo cyclization

Intramolecular cyclization of thiyl and acyl thiyl radicals has been used to access alicyclic and heteorcyclic compounds, via anti-Markovnikov thiol-ene reactions on 1,6-dienes, under photochemical conditions. [15]

Cis–trans conversion of alkenes

Given the reversibility of the thiol-ene radical addition, the reaction can be used to facilitate cis–trans isomerizations. The thiyl radical propagates with the alkene to form a carbon-centered radical, the previous double bond now allows free rotation around the single sigma bond. When the reverse reaction occurs, the orientation of the hydrogen addition on the carbon radical determines whether the isomerization product will be cis or trans. Therefore, composition of the products depends on the conformational stability of the carbon-centered radical intermediate. [16]

Thiol-ene cis-trans isomerization Thiol-Ene Cis-trans isomerization.png
Thiol-ene cis–trans isomerization

Potential applications

Dendrimer synthesis

Dendrimers are promising in medicine, biomaterials, and nanoengineering. These polymers can functions as targeting components, detecting agents, and pharmaceutically-active compounds. Thiol-ene additions are useful in the divergent synthesis of dendrimers due to the characteristics of click chemistry such as the mild reaction conditions (benign solvents), regioselectivity, high efficiency, high conversion and quantitative yield. [17] Because this reaction is photo-initiated, it does not require copper catalysis, unlike other common reactions used in dendrimer preparation; this is advantageous for the synthesis of functional biomaterials given the inhibitory characteristic of copper on biological systems. [18] Thiol-ene reactions have been used alongside anhydride, esterification, Grignard, and Michael reactions to functionalize chain ends and build polymer backbones in the synthesis of branched molecules such as glycodendrons, polythioether dendrimers and organosilicon thioether dendrimers. [3] [4] [19]

A general strategy for the divergent synthesis of a dendrimer begins with a core; commonly-used cores include 2,4,6-triallyloxy-1,3,5-triazine, triallyl isocyanurate and tetravinylsilane. [17] [18] [20] In a well cited report, 2,4,6-triallyloxy-1,3,5-triazine was mixed with 1-thioglycerol in the absence of solvent, the thiol-ene reaction was initiated by the radical initiator 2,2-dimethoxy-2-phenylacetophenone and UV irradiation. Terminal alkene functional groups were added to the dendrimer via esterification by pent-4-enoic anhydride in the presence of DMAP and pyridine. The fourth generation product prepared in a stepwise fashion contains 48 terminal hydroxyl groups [17]

Polymer synthesis

Multifunctional thiols such as pentaerythritol tetrakis(3-mercaptopropionate) can react with multifunctional enes such as norbornene-functionalized monomers, by photopolymerization to form cross-linked polymer networks. These thiol-ene networks are advantageous over traditional networks in that they form rapidly and quantitatively under atmospheric conditions (no oxygen inhibition) to form homogeneous polymer networks. [4]

Surface patterning

The thiol-ene functionalization of surface has been widely investigated in material science and biotechnology. The attachment of a molecule with a sterically accessible alkene or thiol group to a solid surface enables the construction of polymers on the surface through subsequent thiol-ene reactions. [2] Given that in aqueous solutions thiol-ene reactions can be initiated by UV light (wavelength 365–405 nm) or sunlight, the attachment of a given functional group to the exposed thiol or alkene can be controlled spatially through photomasking. [21] More specifically, a photomask, enables the selective exposure of a surface to a UV light source, controlling the location of a given thiol-ene reaction, whereas the identity of the attached molecule is determined by the composition of the aqueous phase placed above the surface at the time of UV exposure. Thus, the manipulation of the shape of the photomask and the composition of the aqueous layer results in the creation of heterogeneous surface, whose properties depend on identity of the attached molecule at a given location. [2]

Thiol-ene functionalization of a surface can be achieved with a high level of spatial specificity, allowing the production of photomasks. [21]

Organo-triethoxysilane molecules, either thiol or vinyl tailed, have been introduced in surface functionalization. Ethoxysilane and methoxysilane functional groups are commonly used to anchor organic molecules on a variety of oxides surfaces. The thiol-ene coupling can be achieved either in the bulk solution before molecular anchoring [8] or step-wise onto a substrate that enables photolithography. [22] The reaction can be done in five minutes under sunlight that has ~4% UV light that is useful for the thiol-ene reaction. [8]

Protein patterning on electron beam resist

Thiol-ene can also be used as an electron beam resist,[ clarification needed ] resulting in nanostructures that allow direct protein functionalization. [23]

See also

Related Research Articles

<span class="mw-page-title-main">Alkene</span> Hydrocarbon compound containing one or more C=C bonds

In organic chemistry, an alkene, or olefin, is a hydrocarbon containing a carbon–carbon double bond. The double bond may be internal or in the terminal position. Terminal alkenes are also known as α-olefins.

<span class="mw-page-title-main">Polymerization</span> Chemical reaction to form polymer chains

In polymer chemistry, polymerization, or polymerisation, is a process of reacting monomer molecules together in a chemical reaction to form polymer chains or three-dimensional networks. There are many forms of polymerization and different systems exist to categorize them.

<span class="mw-page-title-main">Organic sulfide</span> Organic compound with an –S– group

In organic chemistry, a sulfide or thioether is an organosulfur functional group with the connectivity R−S−R' as shown on right. Like many other sulfur-containing compounds, volatile sulfides have foul odors. A sulfide is similar to an ether except that it contains a sulfur atom in place of the oxygen. The grouping of oxygen and sulfur in the periodic table suggests that the chemical properties of ethers and sulfides are somewhat similar, though the extent to which this is true in practice varies depending on the application.

<span class="mw-page-title-main">Living polymerization</span> Chain-growth polymerization without the ability to terminate

In polymer chemistry, living polymerization is a form of chain growth polymerization where the ability of a growing polymer chain to terminate has been removed. This can be accomplished in a variety of ways. Chain termination and chain transfer reactions are absent and the rate of chain initiation is also much larger than the rate of chain propagation. The result is that the polymer chains grow at a more constant rate than seen in traditional chain polymerization and their lengths remain very similar. Living polymerization is a popular method for synthesizing block copolymers since the polymer can be synthesized in stages, each stage containing a different monomer. Additional advantages are predetermined molar mass and control over end-groups.

<span class="mw-page-title-main">Epoxide</span> Organic compounds with a carbon-carbon-oxygen ring

In organic chemistry, an epoxide is a cyclic ether, where the ether forms a three-atom ring: two atoms of carbon and one atom of oxygen. This triangular structure has substantial ring strain, making epoxides highly reactive, more so than other ethers. They are produced on a large scale for many applications. In general, low molecular weight epoxides are colourless and nonpolar, and often volatile.

In chemistry, intramolecular describes a process or characteristic limited within the structure of a single molecule, a property or phenomenon limited to the extent of a single molecule.

<span class="mw-page-title-main">Organolithium reagent</span> Chemical compounds containing C–Li bonds

In organometallic chemistry, organolithium reagents are chemical compounds that contain carbon–lithium (C–Li) bonds. These reagents are important in organic synthesis, and are frequently used to transfer the organic group or the lithium atom to the substrates in synthetic steps, through nucleophilic addition or simple deprotonation. Organolithium reagents are used in industry as an initiator for anionic polymerization, which leads to the production of various elastomers. They have also been applied in asymmetric synthesis in the pharmaceutical industry. Due to the large difference in electronegativity between the carbon atom and the lithium atom, the C−Li bond is highly ionic. Owing to the polar nature of the C−Li bond, organolithium reagents are good nucleophiles and strong bases. For laboratory organic synthesis, many organolithium reagents are commercially available in solution form. These reagents are highly reactive, and are sometimes pyrophoric.

In organic chemistry, free-radical addition is an addition reaction which involves free radicals. Radical additions are known for a variety of unsaturated substrates, both olefinic or aromatic and with or without heteroatoms.

<span class="mw-page-title-main">Ene reaction</span> Reaction in organic chemistry

In organic chemistry, the ene reaction is a chemical reaction between an alkene with an allylic hydrogen and a compound containing a multiple bond, in order to form a new σ-bond with migration of the ene double bond and 1,5 hydrogen shift. The product is a substituted alkene with the double bond shifted to the allylic position.

<span class="mw-page-title-main">Wacker process</span> Chemical reaction

The Wacker process or the Hoechst-Wacker process refers to the oxidation of ethylene to acetaldehyde in the presence of palladium(II) chloride and copper(II) chloride as the catalyst. This chemical reaction was one of the first homogeneous catalysis with organopalladium chemistry applied on an industrial scale.

<span class="mw-page-title-main">Norbornene</span> Chemical compound

Norbornene or norbornylene or norcamphene is a highly strained bridged cyclic hydrocarbon. It is a white solid with a pungent sour odor. The molecule consists of a cyclohexene ring with a methylene bridge between carbons 1 and 4. The molecule carries a double bond which induces significant ring strain and significant reactivity.

<span class="mw-page-title-main">Enol ether</span> Class of chemical compounds

In organic chemistry an enol ether is an alkene with an alkoxy substituent. The general structure is R2C=CR-OR where R = H, alkyl or aryl. A common subfamily of enol ethers are vinyl ethers, with the formula ROCH=CH2. Important enol ethers include the reagent 3,4-dihydropyran and the monomers methyl vinyl ether and ethyl vinyl ether.

Ring-closing metathesis (RCM) is a widely used variation of olefin metathesis in organic chemistry for the synthesis of various unsaturated rings via the intramolecular metathesis of two terminal alkenes, which forms the cycloalkene as the E- or Z- isomers and volatile ethylene.

<span class="mw-page-title-main">Photopolymer</span>

A photopolymer or light-activated resin is a polymer that changes its properties when exposed to light, often in the ultraviolet or visible region of the electromagnetic spectrum. These changes are often manifested structurally, for example hardening of the material occurs as a result of cross-linking when exposed to light. An example is shown below depicting a mixture of monomers, oligomers, and photoinitiators that conform into a hardened polymeric material through a process called curing.

<span class="mw-page-title-main">Hydroamination</span> Addition of an N–H group across a C=C or C≡C bond

In organic chemistry, hydroamination is the addition of an N−H bond of an amine across a carbon-carbon multiple bond of an alkene, alkyne, diene, or allene. In the ideal case, hydroamination is atom economical and green. Amines are common in fine-chemical, pharmaceutical, and agricultural industries. Hydroamination can be used intramolecularly to create heterocycles or intermolecularly with a separate amine and unsaturated compound. The development of catalysts for hydroamination remains an active area, especially for alkenes. Although practical hydroamination reactions can be effected for dienes and electrophilic alkenes, the term hydroamination often implies reactions metal-catalyzed processes.

<span class="mw-page-title-main">Thiol-yne reaction</span>

The thiol-yne reaction is an organic reaction between a thiol and an alkyne. The reaction product is an alkenyl sulfide. The reaction was first reported in 1949 with thioacetic acid as reagent and rediscovered in 2009. It is used in click chemistry and in polymerization, especially with dendrimers.

<span class="mw-page-title-main">Vinyl iodide functional group</span>

In organic chemistry, a vinyl iodide functional group is an alkene with one or more iodide substituents. Vinyl iodides are versatile molecules that serve as important building blocks and precursors in organic synthesis. They are commonly used in carbon-carbon forming reactions in transition-metal catalyzed cross-coupling reactions, such as Stille reaction, Heck reaction, Sonogashira coupling, and Suzuki coupling. Synthesis of well-defined geometry or complexity vinyl iodide is important in stereoselective synthesis of natural products and drugs.

<span class="mw-page-title-main">Photoredox catalysis</span>

Photoredox catalysis is a branch of photochemistry that uses single-electron transfer. Photoredox catalysts are generally drawn from three classes of materials: transition-metal complexes, organic dyes, and semiconductors. While organic photoredox catalysts were dominant throughout the 1990s and early 2000s, soluble transition-metal complexes are more commonly used today.

Hydrophosphination is the insertion of a carbon-carbon multiple bond into a phosphorus-hydrogen bond forming a new phosphorus-carbon bond. Like other hydrofunctionalizations, the rate and regiochemistry of the insertion reaction is influenced by the catalyst. Catalysts take many forms, but most prevalent are bases and free-radical initiators. Most hydrophosphinations involve reactions of phosphine (PH3).

<span class="mw-page-title-main">Allyl glycidyl ether</span> Chemical compound

Allyl glycidyl ether is an organic compound used in adhesives and sealants and as a monomer for polymerization reactions. It is formally the condensation product of allyl alcohol and glycidol via an ether linkage. Because it contains both an alkene and an epoxide group, either group can be reacted selectively to yield a product where the other functional group remains intact for future reactions.

References

  1. ↑ Posner, Theodor (January 1905). "Beiträge zur Kenntniss der ungesättigten Verbindungen. II. Ueber die Addition von Mercaptanen an ungesättigte Kohlenwasserstoffe". Berichte der Deutschen Chemischen Gesellschaft. 38 (1): 646–657. doi:10.1002/cber.190503801106.
  2. 1 2 3 4 Lowe, Andrew B. (2010). "Thiol-ene "click" reactions and recent applications in polymer and materials synthesis". Polym. Chem. 1 (1): 17–36. doi:10.1039/B9PY00216B.
  3. 1 2 Nilsson, Camilla; Simpson, Neil; Malkoch, Michael; Johansson, Mats; Malmström, Eva (15 February 2008). "Synthesis and thiol-ene photopolymerization of allyl-ether functionalized dendrimers". Journal of Polymer Science Part A: Polymer Chemistry. 46 (4): 1339–1348. Bibcode:2008JPoSA..46.1339N. doi:10.1002/pola.22474.
  4. 1 2 3 4 5 6 7 Hoyle, Charles E.; Bowman, Christopher N. (22 February 2010). "Thiol-Ene Click Chemistry". Angewandte Chemie International Edition. 49 (9): 1540–1573. doi:10.1002/anie.200903924. PMID   20166107.
  5. 1 2 3 Northrop, Brian H.; Coffey, Roderick N. (22 August 2012). "Thiol–Ene Click Chemistry: Computational and Kinetic Analysis of the Influence of Alkene Functionality". Journal of the American Chemical Society. 134 (33): 13804–13817. doi:10.1021/ja305441d. PMID   22853003.
  6. ↑ Nair, Devatha P.; Podgórski, Maciej; Chatani, Shunsuke; Gong, Tao; Xi, Weixian; Fenoli, Christopher R.; Bowman, Christopher N. (14 January 2014). "The Thiol-Michael Addition Click Reaction: A Powerful and Widely Used Tool in Materials Chemistry". Chemistry of Materials. 26 (1): 724–744. doi:10.1021/cm402180t.
  7. 1 2 Fındık, Volkan; Degirmenci, Isa; Çatak, Şaron; Aviyente, Viktorya (January 2019). "Theoretical investigation of thiol-ene click reactions: A DFT perspective". European Polymer Journal. 110: 211–220. Bibcode:2019EurPJ.110..211F. doi:10.1016/j.eurpolymj.2018.11.030. S2CID   105594327.
  8. 1 2 3 4 Sy Piecco, Kurt W. E.; Aboelenen, Ahmed M.; Pyle, Joseph R.; Vicente, Juvinch R.; Gautam, Dinesh; Chen, Jixin (2018). "Kinetic Model under Light-Limited Condition for Photoinitiated Thiol–Ene Coupling Reactions". ACS Omega. 3 (10): 14327–14332. doi:10.1021/acsomega.8b01725. PMC   6210074 . PMID   30411064.
  9. ↑ Lynch, Dylan M.; Scanlan, Eoin M. (2020-07-07). "Thiyl Radicals: Versatile Reactive Intermediates for Cyclization of Unsaturated Substrates". Molecules. 25 (13): 3094. doi: 10.3390/molecules25133094 . ISSN   1420-3049. PMC   7412111 . PMID   32646036.
  10. ↑ Harrowven, David C; Lucas, Matthew C; Howes, Peter D (June 1999). "Total syntheses of aplysin and debromoaplysin using a diastereoselective, sulfur mediated radical cyclisation strategy". Tetrahedron Letters. 40 (23): 4443–4444. doi:10.1016/S0040-4039(99)00768-6.
  11. ↑ Miyata, Okiko; Ozawa, Yoshiki; Ninomiya, Ichiya; Naito, Takeaki (August 2000). "Radical Cyclization in Heterocycle Synthesis. Part 10: A Concise Synthesis of (−)-Kainic Acid via Sulfanyl Radical Addition–Cyclization–Elimination Reaction". Tetrahedron. 56 (34): 6199–6207. doi:10.1016/S0040-4020(00)00579-2.
  12. ↑ Crick, Peter J.; Simpkins, Nigel S.; Highton, Adrian (2011-12-16). "Synthesis of the Asperparaline Core by a Radical Cascade". Organic Letters. 13 (24): 6472–6475. doi:10.1021/ol202769f. ISSN   1523-7060. PMID   22082317.
  13. ↑ Keck, Gary E.; Wager, Travis T.; Rodriquez, J. Felix Duarte (June 1999). "Total Syntheses of (−)-Lycoricidine, (+)-Lycoricidine, and (+)-Narciclasine via 6- exo Cyclizations of Substituted Vinyl Radicals with Oxime Ethers †". Journal of the American Chemical Society. 121 (22): 5176–5190. doi:10.1021/ja9826688. ISSN   0002-7863.
  14. ↑ Scanlan, Eoin; Corcé, Vincent; Malone, Aoife (19 November 2014). "Synthetic Applications of Intramolecular Thiol-Ene "Click" Reactions". Molecules. 19 (11): 19137–19151. doi: 10.3390/molecules191119137 . PMC   6271571 . PMID   25415476.
  15. ↑ Lynch, Dylan M.; Nolan, Mark D.; Williams, Conor; Van Dalsen, Leendert; Calvert, Susannah H.; Dénès, Fabrice; Trujillo, Cristina; Scanlan, Eoin M. (2023-07-21). "Traceless Thioacid-Mediated Radical Cyclization of 1,6-Dienes". The Journal of Organic Chemistry. 88 (14): 10020–10026. doi:10.1021/acs.joc.3c00824. ISSN   0022-3263. PMC   10367065 . PMID   37418624.
  16. ↑ Walling, Cheves; Helmreich, Wolf (March 1959). "Reactivity and Reversibility in the Reaction of Thiyl Radicals with Olefins". Journal of the American Chemical Society. 81 (5): 1144–1148. doi:10.1021/ja01514a032.
  17. 1 2 3 Killops, Kato L.; Campos, Luis M.; Hawker, Craig J. (April 2008). "Robust, Efficient, and Orthogonal Synthesis of Dendrimers via Thiol-ene "Click" Chemistry". Journal of the American Chemical Society. 130 (15): 5062–5064. CiteSeerX   10.1.1.658.8715 . doi:10.1021/ja8006325. PMID   18355008.
  18. 1 2 Montañez, Maria I.; Campos, Luis M.; Antoni, Per; Hed, Yvonne; Walter, Marie V.; Krull, Brandon T.; Khan, Anzar; Hult, Anders; Hawker, Craig J.; Malkoch, Michael (27 July 2010). "Accelerated Growth of Dendrimers via Thiol−Ene and Esterification Reactions". Macromolecules. 43 (14): 6004–6013. Bibcode:2010MaMol..43.6004M. CiteSeerX   10.1.1.661.7797 . doi:10.1021/ma1009935.
  19. ↑ Rissing, Christiana; Son, David Y. (8 June 2009). "Application of Thiol−Ene Chemistry to the Preparation of Carbosilane−Thioether Dendrimers". Organometallics. 28 (11): 3167–3172. doi:10.1021/om9001395.
  20. ↑ Son, D. Y.; Rissing, C.; Chen, L.; Andersson, T. E. (2010). "Thiol-ene Chemistry for the Synthesis and Modification of Branched Organosilicon Polymers". Polymer Preprints. 51 (2): 730–731.
  21. 1 2 Jonkheijm, Pascal; Weinrich, Dirk; Köhn, Maja; Engelkamp, Hans; Christianen, Peter C. M.; Kuhlmann, Jürgen; Maan, Jan C.; Nüsse, Dirk; Schroeder, Hendrik; Wacker, Ron; Breinbauer, Rolf; Niemeyer, Christof M.; Waldmann, Herbert (26 May 2008). "Photochemical Surface Patterning by the Thiol-Ene Reaction". Angewandte Chemie International Edition. 47 (23): 4421–4424. doi:10.1002/anie.200800101. hdl: 2066/71919 . PMID   18428169.
  22. ↑ Kurt Waldo E. Sy Piecco; Juvinch R. Vicente; Joseph R. Pyle; David C. Ingram; Martin E. Kordesch; Jixin Chen (2019). "Reusable Chemically-Micropatterned Substrates via Sequential Photoinitiated Thiol-Ene Reactions as Template for Perovskite Thin-Film Microarrays". ChemRxiv. doi:10.26434/chemrxiv.8966297.v2.
  23. ↑ Shafagh, Reza; Vastesson, Alexander; Guo, Weijin; van der Wijngaart, Wouter; Haraldsson, Tommy (2018). "E-Beam Nanostructuring and Direct Click Biofunctionalization of Thiol–Ene Resist". ACS Nano. 12 (10): 9940–9946. doi:10.1021/acsnano.8b03709. PMID   30212184. S2CID   52271550.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.