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

Abstract

The preparation of alkynes from carbonyl compounds via a one-carbon homologation has become a very useful pathway for the synthesis of acetylenic compounds, both internal and terminal. This tutorial review provides an overview of the different methods available for this transformation, including their scope and limitations, recent developments and applications in total syntheses.

Recent advances in alkylidene carbene chemistry

“…Representative examples are in his syntheses of oxo-T-cadinol and (À)-morphine (Scheme 111). 121 In both cases, cis [6,5] ring junctions are formed in the alkylidene carbene step, although trans formation is clearly possible, as described above.…”

“…2,7,21e,22,107c,121,126 While the conversion of aldehydes to alkynes has not been discussed in detail in this review, it is nonetheless a powerful tool for the synthetic organic chemist. 6 In particular, the OhiraeBestmann reagent 254 (Fig. 9) has been utilized extensively in natural product synthesis.…”

“…3 The use of hypervalent alkynyl iodides as precursors to alkylidene carbenes has been previously reviewed, 4 as has the use of a-heteroatom substituted alkenyl lithium reagents. 5 A 2010 review by Koskinen discussed developments in the conversion of carbonyl compounds to alkynes, 6 and as such, the synthetic utility of this transformation will not be extensively covered.…”

Convenient Synthesis of Terminal Alkynes from anti‐3‐Aryl‐2,3‐dibromopropanoic Acids Using a K2CO3/DMSO System

“…A variety of methods have been developed for the preparation of terminal alkynes, 5 including the Corey-Fuchs, 6 Seyferth-Gilbert, 7 Colvin rearrangement, 8 and alkyne zipper reactions. 9 However, these procedures generally require a strong base and low temperatures, which limit their use with delicate substrates.…”

Enantiospecific Alkynylation of Alkylboronic Esters

“…[5] Alkyne-substituted stereocenters can be installed with high enantioselectivity by anumber of methods,including the asymmetric addition of acetylides to carbonyls, [6] transformation of chiral aldehydes or ketones into the corresponding alkynes, [7] and coppercatalyzed allylic substitution reactions. [8] As an alternative,we considered stereospecific conversion of chiral alkylboronic esters into alkynes because alkylboronic esters themselves are versatile intermediates that can be readily prepared with high enantioselectivity using av ariety of methods, [9] including by al ithiation-borylation method developed within our laboratory.…”