Deoxygenative debromination of α-bromo-β-hydroxy (acetoxy) phenyl sulfones with samarium(II) iodide led to substituted α,β-unsaturatedsulfones in good to excellent yields. The E-isomer is the major product. A possible mechanism via an α-sulfonyl radical pathway is proposed.
New Peterson reagents were prepared by introducing alkyloxy groups on the silicon atom in order to fix the conformation of the sulfone anion. The reagents 1d and 1e reacted with a variety of aldehydes after the treatment with Li-base to give Z-alpha,beta-unsaturated sulfones with up to >99:1 selectivity in good to excellent yields. For the reaction with aliphatic aldehydes, CPME (cyclopentyl methyl ether) is the choice of solvent, while DME (1,2-dimethoxyethane) gave higher selectivity for the reaction with aromatic aldehydes.
Free radical addition-fragmentation reaction for the preparation of vinyl sulfones and phosphine oxides