A facile ring-opening reaction of cyclobutenes: application to a synthesis of vitamin D3

Abstract The extraordinary accelerating effects of arylsulfinyl, arylsulfonyl, and diphenylphosphinoyl carbanion substituents for cyclobutene ring-opening reaction of bicyclo[4.2.0]-oct-l(6)-ene derivatives are described. The scope and limitation of this new type of reaction, and the application of the dienes so generated by this method for the synthesis of vitamin D 3 , are also discussed.