A novel product pattern in the palladium(II)-catalyzed decomposition of a (1-diazo-2-oxoalkyl)silane

Abstract Elimination of dinitrogen from (3,3-dimethyl-l-diazo-2-oxobutyl)-(tert-butyl)dimethylsilane catalyzed by palladium(II) chloride bis(acetonitrile), bis[(η 3 -allyl)chloropalladium] or palladium(II) acetate gives the butatriene derivatives (E)- and (Z)-1,4-di[((tert-butyl)dimethylsilyl)oxy]-2,2,7,7-tetramethyl-3,4,5-octatriene, which are the formal dimers of an alkylidene carbene. The siloxyalkene ( t Bu)[Me 2 ( t Bu)SiO]CChCl is also formed, with a yield which parallels the amount of catalyst. Similarly, ( t Bu)[Me 2 ( t Bu)SiO]C(OAc) is a by product, when the decomposition of the same diazoketone is catalysed by palladium(II) acetate. The structure of the (E) isomer of the bis(siloxy)-3,4,5-octatriene derivative was determined by an X-ray diffraction study.