Trialkyltin and trialkylsilyl substituents have been found to activate C-H bonds of alkanes in the ß position toward insertion of dichlorocarbene. The reaction Me3MCH2CH2CH3 + PhHgCCl2Br -* Me3MCH2-CH(CC12H)CH3 + PhHgBr (M = Sn and Si) is typical. A consideration of product yields in 36 such reactions and of the results of relative reactivity studies as well as of the related CC12 insertions into ß C-H bonds of dialkylmercurials (Landgrebe) suggests to us that it is metal-carbon bond hyperconjugation and, to a lesser extent, the +1 inductive effect of the alkylmetal substituents which are the important factors involved and that these operate to stabilize transition state I, in which the carbon atom into whose bond to hydrogen CC12 insertion is occurring bears a partial positive charge. Thirty new siliconor tin-containing products of such CC12 insertion were prepared and characterized during the course of this study.

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Kobalticinium‐hexafluorphosphat (I) geht beim Behandeln mit Natriumhydroxid oder Natriumamid über die diskutierten Zwischenstufen (II) und (III) in Azulen (IV) über.

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A comparative study of catalysis by light and by metals of the isomerisation of cyclododeca-l,5,9-triene has shown that both promote cis-trans double bond isomerisation, but the photochemical reaction also gives a low yield of 1,2,4-trivi nylcyclo hexane. EXPAXIOX and contraction of medium-sized unsaturated rings have been shown to occur under the influence of U.V. irradiation 2 or metal catalysts 394 [see reactions (1) and (Z)]. These results have led us to look for analogous 1