A Complete Diastereo- and Enantioselective Synthesis of 1,2- and 1,3-Diols

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A study on a complete diastereo- and enantioselective synthesis of 1,2- and 1,3-diols has been developed by using our oxazaborolidinone-promoted asymmetric aldol reaction. The stereoselective construction of acyclic systems involving chiral centers was not affected by the stereochemistry of the substrates used in the reaction. This is a novel example of "catalyst control". When such a reaction is repeated, we can get a new strategy of constructing complete controlled diastereoisomers. In order to confirm the effectiveness of the strategy, we chose a mevinic acid lactone derivative of HMG-CoA reductase inhibitors, involving a syn-1,3-diol unit. Our chiral oxazaborolidinone-promoted aldol reaction of 4-phenylbutanal with a silyl ketene acetal containing a dithiolane which allows the production of the corresponding acetate aldol with the level of almost complete enantioselectivity. The second aldol reaction of the aldehyde derived from the first aldol gave the expected syn-1,3-diol by the same catalytic system. The mevinic lactone derivative was very easily synthesized. This is an excellent example of enantioselective acyclic stereoselection under catalyst control.