A convenient scalable one-pot conversion of esters and Weinreb amides to terminal alkynes

Conversion of carbonyl compounds to alkynes: general overview and recent developments

“…39 The starting esters or Weinreb amides (100 mol%) are dissolved in CH 2 Cl 2 and treated at À78 1C with DIBAL-H (120 mol%). After full conversion of the starting material, excess DIBAL-H is quenched by adding MeOH.…”

Bestmann-Ohira Reagent: A Versatile Reagent in Organic Synthesis

“…2 (B) Hamilton D. Dickson and co-workers reported that esters and amides undergo reduction to the corresponding aldehydes using DIBAL-H followed by in situ conversion into terminal alkynes utilizing the Bestmann-Ohira reagent in good to excellent yields. 3 Additionally, chiral nonracemic substrates undergo this transformation with complete preservation of stereochemical integrity. 3 (C) E. Quesada et al described the direct conversion of activated primary alcohols into terminal alkynes through a sequential one-pot, two-step process involving oxidation with manganese dioxide and then treatment with the Bestmann-Ohira reagent.…”

“…3 Additionally, chiral nonracemic substrates undergo this transformation with complete preservation of stereochemical integrity. 3 (C) E. Quesada et al described the direct conversion of activated primary alcohols into terminal alkynes through a sequential one-pot, two-step process involving oxidation with manganese dioxide and then treatment with the Bestmann-Ohira reagent. This transformation proceeds efficiently (59-99% yield) under mild reaction conditions with a range of benzylic, heterocyclic, and propargylic alcohols.…”

A facile synthesis of N-Fmoc protected amino/peptidyl Weinreb amides employing acid chlorides as key intermediates

“…Much of their application in this field stems from the need for N-protected amino aldehydes which are important intermediates for many chemo selective transformations. 4 They are also useful in the synthesis of acetylenes 5 which are starting materials for the popular click reactions. 6 Reduction of Weinreb amides derived from Nprotected amino acids gives the corresponding aldehydes readily and this would give a better protocol for the synthesis of N-Fmoc-α-amino aldehydes which otherwise have to be synthesized either through the oxidation of corresponding alcohols or by careful reduction of esters.…”