Dioxo-molybdenum(VI) and -tungsten(VI) BINOL and alkoxide complexes: Synthesis and catalysis in sulfoxidation, olefin epoxidation and hydrosilylation of carbonyl groups

The reaction of MoO(2)(mes)(2) with S-H(2)BINOL (mes = 2,4,6-Me(3)C(6)H(2); H(2)BINOL = 1,1'-bi-2-naphthol) and (CF(3))(2)MeCOH in THF yielded the novel dioxo-molybdenum(VI) complexes MoO(2)(S-BINOL)(THF)(2) and MoO(2)[OCMe(CF(3))(2)](2)(THF), respectively. Similar tungsten derivatives WO(2)(S-BINOL)(THF) and WO(2)[OCMe(CF(3))(2)](2)(THF) have been prepared by the reaction of WO(2)Cl(2)(DME) with the corresponding lithium salts of BINOL and 1,1,1,3,3,3-hexafluoro-2-methyl-2-propanol, respectively. Catalytic experiments have shown that MoO(2)(S-BINOL)(THF)(2) is an active catalyst in the sulfoxidation of methyl phenyl sulfide and in the epoxidation of cis-cyclooctene with tert-butylhydroperoxide, under mild conditions. The BINOL complex was, however, not found to be enantioselective. In addition, the catalytic activity of the molybdenum species MoO(2)(S-BINOL)(THF)(2) and MoO(2)[OCMe(CF(3))(2)](2)(THF) in the hydrosilylation of carbonyl groups has been explored. (c) 2007 Elsevier B.V. All rights reserved.