THE INVENTION OF NEW RADICAL CHAIN REACTIONS. PART X. HIGH YIELD RADICAL ADDITION REACTIONS OF αβ-UNSATURATED NITROOLEFINS. AN EXPEDIENT CONSTRUCTION OF THE 25-HYDROXY-VITAMIN D3 SIDE CHAIN FROM BILE ACIDS.

Article abstract of DOI:10.1016/S0040-4020(01)91351-1

Radicals derived from thiohydroxamic esters 3 readily add to nitroolefins 5 (Z=NO2) to give good yields of α-nitrosulphides.These adducts, where the structure permits, are easily oxidised to carboxylic acids 8 by treatment with alkaline hydrogen peroxide.Reductive cleavage to the corresponding aldehydes or ketones 9 is efficiently carried out by the action of TiCl3.Addition of methyl magnesium iodide to methyl ketone derived from 3α-acetoxy 11-oxo cholanic acid gives steroid 10 possessing the 25-hydroxycholesterol side chain of the vitamin D₃ metabolites.Radical additions to 1-phenylthio-2-nitropropene 11 have been briefly studied.