Examples
Aminomethylphosphonic acid, the simplest possible aminophosphonate.
Glyphosate, a common though contentious herbicide
Aminophosphonates are organophosphorus compounds with the formula (RO)2P(O)CR'2NR"2. These compounds are structural analogues of amino acids in which a carboxylic moiety is replaced by phosphonic acid or related groups. [1] Acting as antagonists of amino acids, they inhibit enzymes involved in amino acid metabolism and thus affect the physiological activity of the cell. These effects may be exerted as antibacterial, plant growth regulatory or neuromodulatory. They can act as ligands, and heavy metal complexes with aminophosphonates have had medical applications investigated. [2]
Phosphonates are more difficult to hydrolyse than phosphates. [3]
Aminophosphonates are often prepared by hydrophosphonylation, usually the condensation of imines and phosphorous acid. In the Pudovik reaction or Kabachnik–Fields reaction the esters of phosphorous acid are employed, e.g. diphenylphosphite. Because these compounds are of pharmaceutical interest, methods have been developed to induce these additions asymmetrically. [4] [5]
Pyrrole is a heterocyclic aromatic organic compound, a five-membered ring with the formula C4H4NH. It is a colorless volatile liquid that darkens readily upon exposure to air. Substituted derivatives are also called pyrroles, e.g., N-methylpyrrole, C4H4NCH3. Porphobilinogen, a trisubstituted pyrrole, is the biosynthetic precursor to many natural products such as heme.
An imine is a functional group or chemical compound containing a carbon–nitrogen double bond. The nitrogen atom can be attached to a hydrogen (H) or an organic group (R). If this group is not a hydrogen atom, then the compound can sometimes be referred to as a Schiff base. The carbon atom has two additional single bonds. The term "imine" was coined in 1883 by the German chemist Albert Ladenburg.
A nitrile is any organic compound that has a −C≡N functional group. The prefix cyano- is used interchangeably with the term nitrile in industrial literature. Nitriles are found in many useful compounds, including methyl cyanoacrylate, used in super glue, and nitrile rubber, a nitrile-containing polymer used in latex-free laboratory and medical gloves. Nitrile rubber is also widely used as automotive and other seals since it is resistant to fuels and oils. Organic compounds containing multiple nitrile groups are known as cyanocarbons.
Chalcone is an aromatic ketone and an enone that forms the central core for a variety of important biological compounds, which are known collectively as chalcones or chalconoids. Alternative names for chalcone include benzylideneacetophenone, phenyl styryl ketone, benzalacetophenone, β-phenylacrylophenone, γ-oxo-α,γ-diphenyl-α-propylene, and α-phenyl-β-benzoylethylene.
The Mannich reaction is an organic reaction which consists of an amino alkylation of an acidic proton placed next to a carbonyl functional group by formaldehyde and a primary or secondary amine or ammonia. The final product is a β-amino-carbonyl compound also known as a Mannich base. Reactions between aldimines and α-methylene carbonyls are also considered Mannich reactions because these imines form between amines and aldehydes. The reaction is named after chemist Carl Mannich.
Phosphorous acid, is the compound described by the formula H3PO3. This acid is diprotic (readily ionizes two protons), not triprotic as might be suggested by this formula. Phosphorous acid is an intermediate in the preparation of other phosphorus compounds. Organic derivatives of phosphorous acid, compounds with the formula RPO3H2, are called phosphonic acids.
Pyrazole is an organic compound with the formula C3H3N2H. It is a heterocycle characterized by a 5-membered ring of three carbon atoms and two adjacent nitrogen atoms. Pyrazole is a weak base, with pKb 11.5 (pKa of the conjugated acid 2.49 at 25 °C). Pyrazoles are also a class of compounds that have the ring C3N2 with adjacent nitrogen atoms. Notable drugs containing a pyrazole ring are celecoxib (Celebrex) and the anabolic steroid stanozolol.
Phosphonates and phosphonic acids are organophosphorus compounds containing C−PO(OH)2 or C−PO(OR)2 groups (where R = alkyl, aryl). Phosphonic acids, typically handled as salts, are generally nonvolatile solids that are poorly soluble in organic solvents, but soluble in water and common alcohols. Many commercially important compounds are phosphonates, including glyphosate (the active molecule of the herbicide "Roundup"), and ethephon, a widely used plant growth regulator. Bisphosphonates are popular drugs for treatment of osteoporosis.
The Petasis reaction is the multi-component reaction of an amine, a carbonyl, and a vinyl- or aryl-boronic acid to form substituted amines.
The Chichibabin pyridine synthesis is a method for synthesizing pyridine rings. In its general form, the reaction can be described as a condensation reaction of aldehydes, ketones, α,β-Unsaturated carbonyl compounds, or any combination of the above, in ammonia or ammonia derivatives. It was reported by Aleksei Chichibabin in 1924. The following is the overall form of the general reaction:
In organophosphorus chemistry, the Kabachnik–Fields reaction is a three-component organic reaction forming α-aminomethylphosphonates from an amine, a carbonyl compound, and a dialkyl phosphonate, (RO)2P(O)H (that are also called dialkylphosphites). Aminophosphonates are synthetic targets of some importance as phosphorus analogues of α-amino acids (a bioisostere). This multicomponent reaction was independently discovered by Martin Izrailevich Kabachnik and Ellis K. Fields in 1952. The reaction is very similar to the two-component Pudovik reaction, which involves condensation of the phosphite and a preformed imine.
Oxazoline is a five-membered heterocyclic chemical compound containing one atom each of oxygen and nitrogen. It was likely first synthesized in 1884 but it was not until 5 years later that Siegmund Gabriel correctly assigned the structure. It was named in-line with the Hantzsch–Widman nomenclature and is part of a family of heterocyclic compounds, where it exists between oxazole and oxazolidine in terms of saturation.
The Enders SAMP/RAMP hydrazone alkylation reaction is an asymmetric carbon-carbon bond formation reaction facilitated by pyrrolidine chiral auxiliaries. It was pioneered by E. J. Corey and D. Enders in 1976, and was further developed by D. Enders and his group. This method is usually a three-step sequence. The first step is to form the hydrazone between (S)-1-amino-2-methoxymethylpyrrolidine (SAMP) or (R)-1-amino-2-methoxymethylpyrrolidine (RAMP) and a ketone or aldehyde. Afterwards, the hydrazone is deprotonated by lithium diisopropylamide (LDA) to form an azaenolate, which reacts with alkyl halides or other suitable electrophiles to give alkylated hydrazone species with the simultaneous generation of a new chiral center. Finally, the alkylated ketone or aldehyde can be regenerated by ozonolysis or hydrolysis.
N-Sulfinyl imines are a class of imines bearing a sulfinyl group attached to nitrogen. These imines display usefully stereoselectivity reactivity and due to the presence of the chiral electron withdrawing N-sulfinyl group. They allow 1,2-addition of organometallic reagents to imines. The N-sulfinyl group exerts powerful and predictable stereodirecting effects resulting in high levels of asymmetric induction. Racemization of the newly created carbon-nitrogen stereo center is prevented because anions are stabilized at nitrogen. The sulfinyl chiral auxiliary is readily removed by simple acid hydrolysis. The addition of organometallic reagents to N-sulfinyl imines is the most reliable and versatile method for the asymmetric synthesis of amine derivatives. These building blocks have been employed in the asymmetric synthesis of numerous biologically active compounds.
2,5-Diketopiperazine, also known as piperazine-2,5-dione and as the cyclodipeptide cyclo(Gly-Gly), is an organic compound and the smallest cyclic dipeptide that consists of a six-membered ring containing two amide linkages where the two nitrogen atoms and the two carbonyls are at opposite positions in the ring. It was first synthesized by Curtius and Gloebel in 1888 and was the first compound containing a peptide bond to be studied by X-ray crystallography in 1938. It occurs in cocoa and bread and has a metallic and bitter taste.
Borinic acidH
2BOH, also known as boronous acid, is an oxyacid of boron with formula H
2BOH. Borinate is the associated anion of boron with formula H
2BO−
, however being a lewis acid the form in basic solution is H
2B(OH)−
2.
Amino acid N-carboxyanhydrides, also called Leuchs' anhydrides, are reactive derivatives of amino acids. They are classified as N-carboxyanhydrides or NCAs. Typically these compounds are derived from amino acids by treatment with triphosgene. They are white solids, prone to polymerization upon treatment with nucleophiles.
Organoniobium chemistry is the chemistry of compounds containing niobium-carbon (Nb-C) bonds. Compared to the other group 5 transition metal organometallics, the chemistry of organoniobium compounds most closely resembles that of organotantalum compounds. Organoniobium compounds of oxidation states +5, +4, +3, +2, +1, 0, -1, and -3 have been prepared, with the +5 oxidation state being the most common.
In organophosphorus chemistry, the Pudovik reaction is a method for preparing α-aminomethylphosphonates. Under basic conditions, the phosphorus–hydrogen bond of a dialkylphosphite, (RO)2P(O)H, adds across the carbon–nitrogen double bond of an imine (a hydrophosphonylation reaction). The reaction is closely related to the three-component Kabachnik–Fields reaction, where an amine, phosphite, and an organic carbonyl compound are condensed, which was reported independently by Martin Kabachnik and Ellis Fields in 1952. In the Pudovik reaction, a generic imine, RCH=NR', would react with a phosphorous reagent like diethylphosphite as follows:
In chemistry hydrophosphonylation refers to any reaction where addition across a double bond generates a phosphonate (RP(O)(OR')2) group. Examples include the Kabachnik–Fields reaction, where a dialkylphosphite reacts across an imine to form an aminophosphonate. The reaction is catalyzed by bases and is subject to organocatalysis. Important compounds generated by this reaction include the common herbicide glyphosate.