Diastereoselective NaBH4 Reductions of (dl) α‐Keto Esters

The (dl) α‐keto esters 16, were prepared from the (dl) carbinols 1 to 4 and from (dl)‐2‐hydroxyheptahelicene 5. These (dl) α‐keto esters underwent NaBH4 reductions to give the corresponding diastereomeric (dl) α‐hydroxy esters 17, with 54 to ∼100% diastereomeric excesses. Copyright © 1985 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim