Synthetic studies of pestalotiopsin A: asymmetric synthesis of the 2-oxabicyclo[3.2.0]heptane substructure

A functionalized 2-oxabicyclo[3.2.0]heptan-3-one derivative, possessing all the skeletal carbons of pestalotiopsin A, has been synthesized. For the preparation of intermediary cyclobutane derivatives in enantioenriched form, the Lewis acid-catalyzed [2+2] cycloaddition of N-propiolated Oppolzer’s camphorsultam with dimethylketene bis(trimethylsilyl) acetal followed by a stereoselective 1,4-hydride addition/protonation, has been developed.