Organolithium reagents reaction with esters

Chiral boronic esters react with organolithium reagents to form diorganylalkoxyboranes (borinic esters). Subsequent reaction with the anion of dichloromethyl methyl ether then yields chiral ketones by rearrangement of both of the groups on boron (Scheme 42). No racemization is observed in this sequence and alkyl-, aryl- or alkynyl-lithium reagents can be used. 

Silyl nitronates derived from primary and secondary nitroalkanes form oximes on reaction with organolithium reagents. Yields are modest, and the concentration of the reaction is important, as above ca. 0.2 M, the major product becomes the silyl ester of a hydroxamic acid (Scheme 5). 

Reactions of either Grignard or organolithium reagents with most aldehydes, ketones, or esters produce alcohols. Reactions of organolithium reagents with carboxylic acids, or of Grignard reagents with nitriles, produce ketones. 

With organolithium reagents, stable intermediates are produced by addition to a carboxylic acid. On workup, these intermediates produce ketones. As with Grignard reagents, the reaction of organolithium reagents with esters produces tertiary alcohols because the intermediates decompose to ketones under the reaction conditions. The mechanisms for these processes are illustrated in the examples that follow. 

There are several approaches for derivatization of squaric acid (1). The traditional major route relies on the nucleophihc reaction of the eligible esters 5 with organolithium and organomagnesium reagents their addition to 5 is known to be sufficiently selective to give 1,2-addition products 6 (4-substituted 4-hydroxy-2-cyclobutenones) from the former and... 

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