Transformation of organic compounds in the presence of metal complexes. VII. Selective reduction of diketones by hydrosilylation in the presence of rhodium(I) complexes

An investigation was made of the hydrosilylation of 2,2,4,4-tetramethyl-1,3-cyclobutanedione with alkyl- and arylsilanes, catalysed by a variety of rhodium(I) complexes. Tle selectivity of the reduction depends strongly on the steric requirements of the silane molecules. An appropriate selection of hydrosilanes (di- and certain trialkylsilanes) provides a new selective method for the preparation of 3-hydroxy-2,2,4,4-tetramethylcyclobutanone. Diphenylsilane and amylsilane are selective in the formation of isomeric diols, diphenylsilane favouring formation of the cis-diol, and amylsilane yielding mainly the trans-diol.