Efficient and diastereoselective synthesis of (+)‐ and (−)‐grandisol and 2‐[(1<i>R</i>,2<i>S</i>)‐2‐isopropenylcyclobutyl]ethanol (demethylgrandisol) in high purity

Abstract

Abstract Acetone‐sensitized [2 + 2] photocycloaddition of ethylene to chiral butenolides 3 and 15 yields diastereomeric cyclobutanes, which are transformed to (+)‐( 1 ) and (−)‐grandisol ( ent ‐ 1 ) (overall yield 34–36%) and to 2‐[(1 R ,2 S )‐2‐isopropenylcyclobutyl]ethanol (demethylgrandisol) ( 2 ) (overall yield 25%) in five steps.