Alkyne From ketone, homologation

Seyferth-Gilbert homologation Preparation of alkynes from aldehydes and ketones. 402... 

A synthesis of alkynes from esters via a one-carbon homologation is by reaction with 1-lithiomethylbenzotriazole, followed by elimination of the derived benzotriazol-1-ylmethyl ketone tosylhydrazones. ... 

The two syntheses of 11-deoxydaunomycinone are summarized in Schemes 38 and 39 as they are illustrative of the viability of carbene complexes as intermediates in organic synthesis. The synthesis by Dotz and Popall begins with the chelated o-methoxyphenyl carbene complex (275) and the alkyne (276). A single regioisomer of the phenol (277) was obtained in 76% yield in the benzannulation. After protection of the phenol and carbon homologation of the ketone to the acid, an intramolecular Frie-del-Crafts reaction gave the tetracyclic dione (279) in 45% overall yield from (277). This represents a formal synthesis of 11-deoxydaunomycinone (269) since it has been reported that (279) can be converted to (269) by the procedures of Sih and Johnson. ... 

C-C cleavage of strained rings and ketones has been used to develop useful catalytic reactions. For example, vinylcyclopropanes and vinylcyclobutanes react with alkynes (Equation 6.66) to generate products from 5+2 and 6+2 addition processes that form seven- and eight-membered ring products by overall transformations that are homologs of the Diels-Alder reaction. " The mechanism of these catalytic reactions continues to be studied, but these reactions most likely occur by coordination of the olefin to rhodium and insertion of the metal into the cyclopropene or cyclobutane. Decarbonylation of dialkyl ketones, including relatively unstrained cyclic ketones, has been reported and most likely occurs by oxidative addition into the acyl-alkyl C-C bond, subsequent de-insertion of CO, and C-C reductive elimination. 

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