Fluorde ion - Mediated reactions of disubstituted acetylenes Me3SiC CMMe3(M = C, Si, Ge, Sn) with aldehydes and ketones

The CsF/18-crown-6 mediated reactions of disubstituted acetylenes Me3SiC=CM Me3 (M = C, Si, Ge, Sn) with carbonyl compounds in benzene were studied. In all cases the interaction proceeds with cleavage of the SI-C,, bond and ca n be considered as the addition of ethynylsilane to the carbonyl C=O bond. The formation of bissiloxy derivatives was detected for acetylenes with M=S i and Sn. The cleavage of the Ge-C-sp does not occur under the conditions u sed. Transmetallation of 1-trimethylsilyl-2-trimethylstannylacetylene was o bserved to give a mixture of symmetrical bissilyl- and bisstannylacetylenes with the following bis(trimethylsilyl)acetylene addition to the carbonyl c ompound, the bisstannyl analogue being inactive in CsF/18-crown-6 mediated conditions. These processes open a simple way for the synthesis of new ethy nyl-substituted derivatives of germanium and tin.