A Striking Exception to the Chelate Model for Acyclic Diastereocontrol: Efficient Access to a Versatile Propargyl Alcohol for Chemical Synthesis

摘要

The four-step, asymmetric synthesis of a chiral propargyl alcohol >1 from (R)-pantolactone is described. A key feature of the synthesis is a diastereoselective acetylide addition to a chiral α-alkoxy-aldehyde >7, in which unusual Felkin selectivity is observed, despite the potential for chelation control. Crystalline propargyl alcohol >1 is valuable for complex molecule synthesis, and is easy to prepare in multi-gram quantities and high diastereomeric purity.