α- versus β-hydrogen elimination in the formation of propene from an osmacyclobutane
作者:Wolfgang Fischer、Robert T. Hembre、Daniel R. Sidler、Jack R. Norton
DOI:10.1016/s0020-1693(00)92346-6
日期:1992.8
Os(CO)4(CH2CD2CH2) has been prepared from TsOCH2CD2CH2OTs and Na2[Os(CO)4] and used to investigate the mechanism of propylene extrusion from this osmacyclobutane. Propylene is the principal product whether the thermolysis of the osmacyclobutane is carried out in solution or in a gas phase flow system. Control experiments confirm that the osmacyclobutane does not rearrange prior to thermal decomposition, and that no secondary reactions affect the position of the deuterium labels in the propylene after it is formed in the gas phase. Both CH3CD=CHD and CH2DCD=CH2 are formed, indicating that both alpha- and beta-hydrogen elimination mechanisms are operative. The insertion of CO into the osmacyclobutane ring is facile and may be a step in the propylene extrusion mechanism.