O-Acyl Lactates

The presence of an acyl group on the oxygen of lactic acid derivatives allows chemical manipulations to be performed that would otherwise not be feasible with the corresponding unsubstituted analogs. In addition, the functional groups may be used as synthetic handles for further transformations. O-Acetyl lactates are covered as a separate topic in Section 1.4.1. 

The synthesis is completed by Wittig olefination followed by hexakis( er butylisoni-trile)molybdenum-catalyzed elimination of the pivalate to give 207 in 21% overall yield for the six step sequence. The strategy in this synthesis takes advantage of the chirality of the lactic acid to control stereochemistry in the aldol condensation, and it also furnishes the handle to introduce the final unsaturation. 

Acylation of ( S)-ethyl lactate 2 with 2-bromopropionyl bromide gives acylated derivative 208. Intramolecular Grignard reaction produces (5)-2,4-dimethyltetronic acid (209). Through 

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