Unexpected Z-stereoselectivity in the Ramberg-Backlund reaction of diarylsulfones leading to cis-stilbenes:: the effect of aryl substituents and application in the synthesis of the integrastatin nucleus

With certain substituent patterns, benzyl benzyl sulfone systems have been found to give unexpectedly high Z-stereoselectivity (up to E:Z = 1 : 16) in the Meyers variant of the Ramberg-Backlund reaction. A range of sulfones, bearing various aryl substituents, were explored to rationalize this unprecedented selectivity for Z-stilbene systems. This high level of double bond stereocontrol has also been utilized in the synthesis of integrastatin nucleus, the core of two highly bioactive anti-HIV compounds.