Synthesis of the Bestmann-Ohira Reagent

Abstract

The conversion of an aldehyde to a terminal alkyne by means of a one-carbon chain extension is a key reaction in organic synthesis. By using dimethyl 1-diazo-2-oxopropylphosphonate, the Bestmann-Ohira reagent, the transformation can be achieved in one pot. A reliable, convenient sequence for the preparation of the Bestmann-Ohira reagent is described.

alkynes - diazo compounds - carbenoids - phosphorus

References

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A recent application for the preparation of the synthesis of 1:

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<A NAME="RT09006SS-15">15</A>

The reagent is meanwhile commercially available from Digital Chemistry DSC (www.digitalchem.com).

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<A NAME="RT09006SS-17">17</A>

A discussion has taken place on whether the use of NaN₃ in CH₂Cl₂ causes explosions during workup (see sodium azide under http://pubs.acs.org./cen/safety). However, changing the solvent (e.g. to THF) should not lead to a false sense of safety.