133816-70-3Relevant academic research and scientific papers
Characterization of (Z)-cyclooct-2-enylstannanes
Penman, Kerry G.,Kitching, William,Tagliavini, Giuseppe
, p. 1320 - 1325 (1991)
(Z)-Cyclooct-2-enyltrimethylstannanes and -triphenylstannanes have been synthesized and characterized by 1H and 13C NMR spectra, which indicate a predominating unsymmetrical chair-boat arrangement. A mixture of the cis and trans isomers of both the (4-methylcyclooct-2-enyl)- and (8-methylcyclooct-2-enyl)trimethylstannanes (allylic stannanes) results from a sequence commencing with methylcyanocuprate opening of the monoepoxide of 1,3-cyclooctadiene, which is considered to afford regio- and stereoselectively trans-4-methylcyclooct-2-enol. Chlorination of this alcohol with both thionyl chloride and N-chlorosuccinimide/dimethyl sulfide has been conducted and the structures of the chlorides established by NMR methods and use of [1-2H1]-4-methylcyclooct-2-enol. Trimethylstannylation of the chloride mixtures provides the four possible allylic stannanes, with one of the rearranged 8-methyl isomers slightly predominating. NMR spectra of various fractions from preparative gas chromatography have been obtained, and full assignment of the 13C NMR spectra of the isomers is reported. Acidolysis of these fractions (with CF3COOD) proceeds rapidly to yield mixtures of 2H-substituted 3- and 4-methylcyclooctenes, but only one diastereomer of each system appears to be formed, on the basis of the 13C NMR spectra. This implies that electrophile approach to the π-face at the γ-carbon is not influenced by the orientation of the C-Sn bond but is probably dictated by the predominant molecular conformation.
