Catalytic transformations of diazo compounds promoted by platinum(0) and dicationic platinum(II) complexes

Abstract 9-Diazofluorene (DAF) is decomposed either stoichiometrically or catalytically in the presence of the platinum(0) complex [Pt(C 2 H 4 )(PPh 3 ) 2 ] to give difluoren-9-ylidene-hydrazine in high yield. Under analogous reaction conditions, diphenyldiazomethane gives mostly the azine, Ph 2 CNNCPh 2 , while ethyl diazoacetate (EDA) affords, in low yield, a mixture of diethyl fumarate and maleate in approximately 10:1 molar ratio. The cyclopropanation of styrene with EDA is catalyzed by a series of dicationic complexes of the type [PtL 2 (NCCH 3 ) 2 ][Y] 2 (L 2 =2PPh 3 , Ph 2 PCH=CHPPh 2 , Ph 2 PCH 2 CH 2 PPh 2 ; Y=BF 4 , CF 3 SO 3 ) in 1,2-dichloroethane at 60 °C for 24 h. DAF and EDA undergo insertion reactions into the OH bond of alcohols ROH (R=Me, Et, t -Bu, CH 2 CHCH 2 , Ph) at 25 °C in CH 2 Cl 2 –ROH (DAF or EDA–ROH molar ratio 1/20) in the presence of 1% mol of several dicationic platinum(II) complexes to give the corresponding ethers in excellent yields.