ETHYNYLSILANES .3. SYNTHESES OF SOME 2-ORGANOSILICON BICYCLO[2.2.1]HEPTADIENES AND BICYCLO[2.2.1]HEPT-2-ENES

The syntheses of several new 2-organosilicon bicyclo [2.2.1] heptadiene derivatives by the Diels-Alder addition of alkynylsilanes to cyclopentadiene are reported. Reactions were carried out in sealed bombs and temperatures in the range of 180-260° were necessary to obtain the expected cycloaddition products with the acetylenes (CH3)3SiC≡CR (where R = H, COOC2H5, COCH3), (CH3)2(C6H5)SiC≡CH, and (CH3)2Si(C≡CH)2. Atmospheric catalytic hydrogenation of the unsubstituted double bond in the bicyclo addition products from the first three alkynylsilanes yielded the corresponding organosilicon bicyclo[2.2.1]hept-2-enes. Proton magnetic resonance spectral data are reported and several unusual features of the spectra are discussed in the paper. © 1968, American Chemical Society. All rights reserved.