An Improved Approach to Chiral Cyclopentenone Building Blocks. Total Synthesis of Pentenomycin I and Neplanocin A

Abstract

An improved approach to enantiomerically pure hydroxylated cyclopentenones is reported here, which involves intramolecular nitrone cycloaddition of sugar-derived chiral pent-4-enals and hex-5-en-ones-2 followed by N-O bond cleavage, quaternization of the amine thus produced, and finally oxidative elimination of the amino group. Synthesis of pentenomycin I and neplanocin A is described following this methodology.