Dimethyl P-(1-diazo-2-oxopropyl)phosphonate

CAS 90965-06-3, Cat. No EN300-133907
Reagent for Seyferth–Gilbert homologation

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Dimethyl P-(1-diazo-2-oxopropyl)phosphonate (Ohira-Bestmann reagent) is primarily used in Seyferth–Gilbert homologation in terminal acetylenes synthesis^1,2. It is a pale-yellow liquid soluble in most organic solvents but can slowly react with alcohols. The reagent forms vinylidene carbenes in the presence of a base and carbonyl compounds. In the case of aldehydes rearranging proceeds to alkynes and for ketones - to enol ethers. The choice between two variants of the Ohira-Bestmann reagent (methyl or ethyl ester) depends on what alcohol is used as media for the reaction. Besides homologation, the reagent can be used for 1,3-dipolar cycloaddition to form phosphoryl-substituted nitrogen heterocycles: pyrazoles, triazolines, oxazoles, thiazoles, etc.

Synonyms: dimethyl P-(1-diazo-2-oxopropyl)phosphonate (ACI); phosphonic acid, (1-diazo-2-oxopropyl)-, dimethyl ester (9CI); (1-diazo-2-oxopropyl)phosphonic acid dimethyl ester; 1-diazo-1-(dimethyl phosphono)acetone; 1-diazo-1-dimethoxyphosphoryl-propan-2-one; Bestmann reagent; Bestmann-Ohira reagent; dimethyl (1-azo-2-oxopropyl)phosphonate; dimethyl (1-azoacetonyl)phosphonate; dimethyl (1-diazo-2-oxopropyl)phosphonate; dimethyl (acetyldiazomethyl)phosphonate; Ohira's reagent; Ohira-Bestmann phosphonate; Ohira-Bestmann reagent; α-azido-α-(dimethyl phosphono)acetone