3-oxoalkanoate ester 3-oxo-2-

Ethyl 3-oxoalkanoates when not commercially available can be prepared by the acylation of tert-butyl ethyl malonate with an appropriate acid chloride by way of the magnesium enolate derivative. Hydrolysis and decarboxylation in acid solution yields the desired 3-oxo esters [59]. 3-Keto esters can also be prepared in excellent yields either from 2-alkanone by condensation with ethyl chloroformate by means of lithium diisopropylamide (LDA) [60] or from ethyl hydrogen malonate and alkanoyl chloride usingbutyllithium [61]. Alternatively P-keto esters have also been prepared by the alcoholysis of 5-acylated Mel-drum s acid (2,2-dimethyl-l,3-dioxane-4,6-dione). The latter are prepared in almost quantitative yield by the condensation of Meldrum s acid either with an appropriate fatty acid in the presence of DCCI and DMAP [62] or with an acid chloride in the presence of pyridine [62] (Scheme 7). 

A /5-subslituled a-keto ester, methyl 2-oxo-3-phenylbutanoate, is reduced by several yeasts but the selectivity with baker s yeast is not high enough for synthetic purposes165. In contrast, ethyl 3-chloro-2-oxoalkanoates with a chain length of 6 to 13 atoms are reduced with baker s yeast to the (2S)-configurated products in chemical yields of 56-85% and. in most cases, >95%... 

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