In organophosphorus chemistry, the Kabachnik–Fields reaction is a three-component

organic reaction Organic reactions are chemical reactions involving organic compounds. The basic organic chemistry reaction types are addition reactions, elimination reactions, substitution reactions, pericyclic reactions, rearrangement reactions, Mechanistic Organ ...

forming α-aminomethylphosphonates from an

amine In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituen ...

, 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 Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Ear ...

analogues of α-

amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha am ...

s (a bioisostere). This multicomponent reaction was independently discovered by and Ellis K. Fields in 1952. The reaction is very similar to the two-component

Pudovik reaction 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 b ...

, which involves condensation of the phosphite and a preformed imine. : The first step in this reaction is the formation of an imine, followed by a

hydrophosphonylation 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 am ...

step where the phosphonate P-H bond across the C=N double bond. The starting carbonyl component is usually an

aldehyde In organic chemistry, an aldehyde () is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl grou ...

and sometimes a

ketone In organic chemistry, a ketone is a functional group with the structure R–C(=O)–R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group –C(=O)– (which contains a carbon-oxygen double bo ...

. The reaction can be accelerated with a combination of dehydrating reagent and

Lewis acid A Lewis acid (named for the American physical chemist Gilbert N. Lewis) is a chemical species that contains an empty orbital which is capable of accepting an electron pair from a Lewis base to form a Lewis adduct. A Lewis base, then, is any sp ...

. Enantioselective variants of the Kabachnik-Fields reaction have been developed, for example employing α-methylbenzylamine provides a chiral, non-racemic α-aminophosphonate. :

References

{{DEFAULTSORT:Kabachnik-Fields reaction Multiple component reactions Name reactions