Names | |
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Preferred IUPAC name Benzyl carbonochloridate | |
Other names Benzyl chloroformate Benzyloxycarbonyl chloride Z-Chloride | |
Identifiers | |
3D model (JSmol) | |
ChemSpider | |
ECHA InfoCard | 100.007.205 |
EC Number |
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PubChem CID | |
RTECS number |
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UNII | |
UN number | 1739 |
CompTox Dashboard (EPA) | |
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Properties | |
C8H7ClO2 | |
Molar mass | 170.59 g·mol−1 |
Appearance | colorless liquid, may appear yellow due to impurities |
Odor | pungent |
Density | 1.195 g/cm3 |
Boiling point | 103 °C (217 °F; 376 K) (20 Torr) |
degrades | |
Refractive index (nD) | 1.519 (589 nm) |
Hazards | |
GHS labelling: | |
Danger | |
H314, H410 | |
P260, P264, P273, P280, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P321, P363, P391, P405, P501 | |
Flash point | 80 °C (176 °F; 353 K) |
Safety data sheet (SDS) | External MSDS |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
Benzyl chloroformate, also known as benzyl chlorocarbonate or Z-chloride, is the benzyl ester of chloroformic acid. It can be also described as the chloride of the benzyloxycarbonyl (Cbz or Z) group. In its pure form it is a water-sensitive oily colorless liquid, although impure samples usually appear yellow. It possesses a characteristic pungent odor and degrades in contact with water.
The compound was first prepared by Leonidas Zervas in the early 1930s who used it for the introduction of the benzyloxycarbonyl protecting group, which became the basis of the Bergmann-Zervas carboxybenzyl method of peptide synthesis he developed with Max Bergmann. [1] [2] This was the first successful method of controlled peptide chemical synthesis and for twenty years it was the dominant procedure used worldwide until the 1950s. [1] To this day, benzyl chloroformate is often used for amine group protection.
The compound is prepared in the lab by treating benzyl alcohol with phosgene:
Phosgene is used in excess to minimise the production of the carbonate (PhCH2O)2C=O. [3]
The use of phosgene gas in the lab preparation carries a very large health hazard, and has been implicated in the chronic pulmonary disease of pioneers in the usage of the compound such as Zervas. [4]
Benzyl chloroformate is commonly used in organic synthesis for the introduction of the benzyloxycarbonyl (formerly called carboxybenzyl) protecting group for amines. The protecting group is abbreviated Cbz or Z (in honor of discoverer Zervas), hence the alternative shorthand designation for benzyl chloroformate as Cbz-Cl or Z-Cl.
Benzyloxycarbonyl is a key protecting group for amines, suppressing the nucleophilic and basic properties of the N lone pair. This "reactivity masking" property, along with the ability to prevent racemization of Z-protected amines, made the Z group the basis of the Begmann-Zervas synthesis of oligopeptides (1932) where the following general reaction is performed to protect the N-terminus of a serially growing oligopeptide chain: [1] [2]
This reaction was hailed as a "revolution" and essentially started the distinct field of synthetic peptide chemistry. [1] It remained unsurpassed in utility for peptide synthesis until the early 1950s when mixed anhydride and active ester methodologies were developed.
Although the reaction is no longer commonly used for peptides, it is nonetheless very widespread for amine protection in other applications within organic synthesis and total synthesis. Common procedures to achieve protection starting from benzyl chloroformate include:
Alternatively, the Cbz group can be generated by the reaction of an isocyanate with benzyl alcohol (as in the Curtius rearrangement).
Hydrogenolysis in the presence of a variety of palladium-based catalysts is the usual method for deprotection. [1] [7] Palladium on charcoal is typical. [8]
Alternatively, HBr and strong Lewis acids have been used, provided that a trap is provided for the released benzyl carbocation. [9]
When the protected amine is treated by either of the above methods (i.e. by catalytic hydrogenation or acidic workup), it yields a terminal carbamic acid which then readily decarboxylates to give the free amine.
2-Mercaptoethanol can also be used, in the presence of potassium phosphate in dimethylacetamide. [10]
Diphosgene is an organic chemical compound with the formula ClCO2CCl3. This colorless liquid is a valuable reagent in the synthesis of organic compounds. Diphosgene is related to phosgene and has comparable toxicity, but is more conveniently handled because it is a liquid, whereas phosgene is a gas.
A protecting group or protective group is introduced into a molecule by chemical modification of a functional group to obtain chemoselectivity in a subsequent chemical reaction. It plays an important role in multistep organic synthesis.
In organic chemistry, peptide synthesis is the production of peptides, compounds where multiple amino acids are linked via amide bonds, also known as peptide bonds. Peptides are chemically synthesized by the condensation reaction of the carboxyl group of one amino acid to the amino group of another. Protecting group strategies are usually necessary to prevent undesirable side reactions with the various amino acid side chains. Chemical peptide synthesis most commonly starts at the carboxyl end of the peptide (C-terminus), and proceeds toward the amino-terminus (N-terminus). Protein biosynthesis in living organisms occurs in the opposite direction.
The Curtius rearrangement, first defined by Theodor Curtius in 1885, is the thermal decomposition of an acyl azide to an isocyanate with loss of nitrogen gas. The isocyanate then undergoes attack by a variety of nucleophiles such as water, alcohols and amines, to yield a primary amine, carbamate or urea derivative respectively. Several reviews have been published.
The Knorr pyrrole synthesis is a widely used chemical reaction that synthesizes substituted pyrroles (3). The method involves the reaction of an α-amino-ketone (1) and a compound containing an electron-withdrawing group α to a carbonyl group (2).
Di-tert-butyl dicarbonate is a reagent widely used in organic synthesis. Since this compound can be regarded formally as the acid anhydride derived from a tert-butoxycarbonyl (Boc) group, it is commonly referred to as Boc anhydride. This pyrocarbonate reacts with amines to give N-tert-butoxycarbonyl or so-called Boc derivatives. These carbamate derivatives do not behave as amines, which allows certain subsequent transformations to occur that would be incompatible with the amine functional group. The Boc group can later be removed from the amine using moderately strong acids. Thus, Boc serves as a protective group, for instance in solid phase peptide synthesis. Boc-protected amines are unreactive to most bases and nucleophiles, allowing for the use of the fluorenylmethyloxycarbonyl group (Fmoc) as an orthogonal protecting group.
The tert-butyloxycarbonyl protecting group or tert-butoxycarbonyl protecting group is a protecting group used in organic synthesis.
Oseltamivir total synthesis concerns the total synthesis of the antiinfluenza drug oseltamivir marketed by Hoffmann-La Roche under the trade name Tamiflu. Its commercial production starts from the biomolecule shikimic acid harvested from Chinese star anise and from recombinant E. coli. Control of stereochemistry is important: the molecule has three stereocenters and the sought-after isomer is only 1 of 8 stereoisomers.
{{Infobox scientist | name = Max Bergmann | image = | caption = | birth_date = 12 February 1886 | birth_place = Fürth, Germany | nationality = | death_date = 7 November 1944 (aged 58) | death_place = New York City, United States | field = peptide chemistry | work_institution = Kaiser Wilhelm Institute for Leather Research
Rockefeller Institute for Medical Research | alma_mater = Ludwig Maximilian University of Munich, Friedrich Wilhelm University | doctoral_advisor = Ignaz Bloch | doctoral_students = Leonidas Zervas | known_for = Carboxybenzyl protecting group | spouse = Emmy Bergmann [[:de:Emmy Bergmann | children = Peter Bergmann (physicist) }} Max Bergmann was a Jewish-German biochemist. Together with Leonidas Zervas, the discoverer of the group, they were the first to use the carboxybenzyl protecting group for the synthesis of oligopeptides.
The Bergmann azlactone peptide synthesis is a classic organic synthesis process for the preparation of dipeptides.
The Bergmann degradation is a series of chemical reactions designed to remove a single amino acid from the carboxylic acid (C-terminal) end of a peptide. First demonstrated by Max Bergmann in 1934, it is a rarely used method for sequencing peptides. The later developed Edman degradation is an improvement upon the Bergmann degradation, instead cleaving the N-terminal amino acid of peptides to produce a hydantoin containing the desired amino acid.
The Mukaiyama taxol total synthesis published by the group of Teruaki Mukaiyama of the Tokyo University of Science between 1997 and 1999 was the 6th successful taxol total synthesis. The total synthesis of Taxol is considered a hallmark in organic synthesis.
The Achmatowicz reaction, also known as the Achmatowicz rearrangement, is an organic synthesis in which a furan is converted to a dihydropyran. In the original publication by the Polish Chemist Osman Achmatowicz Jr. in 1971 furfuryl alcohol is reacted with bromine in methanol to 2,5-dimethoxy-2,5-dihydrofuran which rearranges to the dihydropyran with dilute sulfuric acid. Additional reaction steps, alcohol protection with methyl orthoformate and boron trifluoride) and then ketone reduction with sodium borohydride produce an intermediate from which many monosaccharides can be synthesised.
Chloroformic acid is a chemical compound with the formula ClCO2H. It is the single acyl-halide derivative of carbonic acid. Chloroformic acid is also structurally related to formic acid, in a way that the non-acidic hydrogen of formic acid is replaced by chlorine. Despite the similar name, it is very different from chloroform. It is described as unstable.
Chloroformates are a class of organic compounds with the formula ROC(O)Cl. They are formally esters of chloroformic acid. Most are colorless, volatile liquids that degrade in moist air. A simple example is methyl chloroformate, which is commercially available.
Trichloroethyl chloroformate is used in organic synthesis for the introduction of the trichloroethyl chloroformate (Troc) protecting group for amines, thiols and alcohols. It readily cleaves vs other carbamates and can be used in an overall protecting group strategy.
Trichloroacetonitrile is an organic compound with the formula CCl3CN. It is a colourless liquid, although commercial samples often are brownish. It is used commercially as a precursor to the fungicide etridiazole. It is prepared by dehydration of trichloroacetamide. As a bifunctional compound, trichloroacetonitrile can react at both the trichloromethyl and the nitrile group. The electron-withdrawing effect of the trichloromethyl group activates the nitrile group for nucleophilic additions. The high reactivity makes trichloroacetonitrile a versatile reagent, but also causes its susceptibility towards hydrolysis.
The fluorenylmethoxycarbonyl protecting group (Fmoc) is a base-labile protecting group used in organic synthesis.
Leonidas Zervas was a Greek organic chemist who made seminal contributions in peptide chemical synthesis. Together with his mentor Max Bergmann they laid the foundations for the field in 1932 with their major discovery, the Bergmann-Zervas carboxybenzoxy oligopeptide synthesis which remained unsurpassed in utility for the next two decades. The carboxybenzyl protecting group he discovered is often abbreviated Z in his honour.
Iphigenia Photaki was a Greek organic chemist remembered for her contributions in peptide chemical synthesis, especially in the synthesis of biologically/enzymatically active peptides.