Ketones, enol, reaction with Grignard reagents

In the general context of donor/acceptor formulation, the carbonyl derivatives (especially ketones) are utilized as electron acceptors in a wide variety of reactions such as additions with Grignard reagents, alkyl metals, enolates (aldol condensation), hydroxide (Cannizzaro reaction), alkoxides (Meerwein-Pondorff-Verley reduction), thiolates, phenolates, etc. reduction to alcohols with lithium aluminum hydride, sodium borohydride, trialkyltin hydrides, etc. and cyloadditions with electron-rich olefins (Paterno-Buchi reaction), acetylenes, and dienes.46... [Pg.212]

The free monomeric hydroxy aldehydes are difficult to obtain by hydrolysis of the oximes. Bromomagnesium enolates prepared from Grignard reagents and sterically hindered ketones act as true Grignard reagents. /3-keto alcohols are formed by their reaction with aldehydes or ketones. ... [Pg.87]

EthytidenationThe ketone (2) undergoes Wittig reaction with ethylidene-triphenylphosphorane in yields of only about 40%, with recovery of 2. The difficulty may be enolization promoted by the basic ylide. Use of the Grignard reagent from a-chloroethyltrimethylsilane results only in reduction of the carbonyl group. The problem is solved by use of 1, which reacts with 2 to give the internal ketal 3. Hydro-... [Pg.442]