Iterative synthesis of (oligo)deoxypropionates via zinc-catalyzed enantiospecific sp3-sp3 cross-coupling.

This group's recently reported mild zinc-catalyzed enantiospecific sp3-sp3 cross-coupling of lactic acid tert-butylester triflate with Grignard reagents was now applied to an iterative approach in the synthesis of a series of all four possible diastereomers of the shown trideoxypropionate. Oligodeoxypropionate structures are a common motif in a large number of biologically relevant natural products of polyketide origin thus making our approach a versatile tool in their synthesis.

Stereospecific and stereodivergent construction of tertiary and quaternary carbon centers through switchable directed/nondirected allylic substitution.

This study introduces the ortho-diphenylphosphanylbenzoate (o-DPPB)/o-DPPB oxide system as a switchable directing/nondirecting leaving group in a copper-mediated allylic substitution with Grignard and organozinc reagents. With this system, the regioselective, stereospecific, and stereodivergent construction of quaternary as well as tertiary carbon centers is possible in a reliable and predictable fashion. Starting from one substrate enantiomer, both optical antipodes of the substitution products are readily available.