The cross-metathesis of vinyltrialkoxy-and vinyltrisiloxysilanes as well as divinyltetraethoxydisiloxane with various allyl alkyl ethers catalyzed by Cl 2 (PCy 3 ) 2 Ru(dCHPh) (I) is presented. The reaction is accompanied by self-metathesis of allyl alkyl ethers. The catalytic examination presented in this paper has allowed us to develop optimum conditions for selective synthesis of 1-silyl-3-alkoxy-propenes (R′O) 3 SiCHdCHOR (where R ) Et, n-Bu, Cy, Ph, PhCH 2 , Gly, Me 3 Si, R′ ) Me, Et, SiMe 3 ) with high preference of the E-isomers (E/Z > 7:1). This allowed the selective isolation of the E-isomer. A stoichiometric study of I with substrates has been carried out. The results are discussed on the basis of a metallacarbene mechanism.

Organic chemistry Z 0200 Catalytic Activity of Rhodium-Siloxide Complexes in Hydrosilylation of Allyl Ethers and Allyl Esters-[16 refs.]. -(MARCINIEC, B.; WALCZUK, E.; BLAZEJEWSKA-CHADYNIAK, P.; CHADYNIAK, D.; KUJAWA-WELTEN, M.; KROMPIEC, S.; Organosilicon Chem. V: From Mol. Mater., [Sci. Contrib. presented

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Mass spectrometric behaviour of (E)-1-silyl-2-alkoxyethenesThe behaviour of ionized organosilicon compounds upon electron impact has been extensively examined. 1 -5 3 ] Cž , has been established to involve primarily elimination of the methyl radical at the silicon atom followed by the loss of acetylene through transfer of a hydrogen atom from theˇ-carbon to the silicon atom (ˇ-transfer). Soderquist and Hassner 6 found that the transfer of R to the silicon (˛-transfer) is an important process in the fragmentation patterns of substituted vinylsilanes, mainly R 0 3 SiC(R) CH 2 (R D D, Br, OMe, OSiMe 3 , Ph). Whereas˛-andˇ-substituted vinylsilanes (R 0 3 Si)(R)C CH 2 and R 0 3 SiCH CHR have become very common silyl reagents used in regio-and stereoselective organic synthesis, 7 there are only a few reports on the substituent effect at silicon and at carbon atoms on the fragmentation mechanism of these class of organometallics. Styrylsilanes, PhCH CHSiR 0 3 , are the only -substituted vinylsilanes whose detailed fragmentation has been resolved. 8 Therefore, the aim of this work was to elucidate the decomposition characteristics of (E)-1-silyl-2-alkoxyethenes (Scheme 1) as the first example of silyl(alkoxy)ethenes containing a functional group (ether) at a carbon atom (R 0 3 SiCH CHOR). These compounds were prepared using the recently developed synthetic method based on cross-disproportionation (silylative coupling) of vinyl-trisubstituted silanes with vinyl alkyl ethers catalysed by ruthenium complexes containing or generating Ru-H and/or Ru-Si bonds. 9 The metastable ion spectrometry and highresolution data were used to complete the fragmentation pathways (Scheme 1).Electron ionization (EI) mass spectra of the (E)-1-silyl-2-alkoxyethenes and their labelled derivatives listed in Table 1 The mass spectra of 1 (M r D 144) and 1-d 9 (M r D 153), revealing the presence of molecular ion peaks, are shown in Fig. 1(a) and 1(b), respectively.The B/E linked scan spectra of 1 Cž and [1-d 9 ] C ions indicate a formation of the ions at m/z 73 and 82 identified as Si(CH 3 ) 3 and Si(CD 3 ) 3 , respectively. The ions at m/z 99 of 1 and 108 of 1-d 9 are formed with the elimination of an ethoxy radical from the molecular ions, although it is a minor process. Further, an abundant ion corresponding to the loss of 15 Da from the molecular ion of 1 is observed at m/z 129. This peak can be assigned to the loss of a methyl radical from the trimethylsilyl group or from the ethyl group of the M Cž ion, since the 129 C ion of 1 corresponds to 135 C in the mass spectrum of 1-d 9 . Therefore, it is evident that the major fragmentation begins with methyl radical loss from the trimethylsilyl group. The B/E linked scan spectrum of the ion 129 C from 1 shows a very intense peak at m/z 103 corresponding to the loss of C 2 H 2 , which is followed by a transfer of the ethoxy group to the silicon. An acetylene elimination has been observed in the mass spectra of the other (E)-1-trimethylsilyl-2-alkoxyethenes, (CH 3 ) 3 SiCH CHOR (R D C 3 H 7 , C 4 ...