REACTIONS OF TETRAMESITYLDISILENE WITH ACID-CHLORIDES AND KETENES

Tetramesityldisilene(1) reacts with dimethylketene and diphenylketene by [2+2] cycloaddition to the carbonyl group to give 3-methylidene-1,2 -disilaoxetanes, 4b and 4c. Acetyl and dimethylacetyl chlorides react with 1 with elimination of HCI to give similar products, 4a and 4b, al ong with 1,1,2,2-tetramesityl-1-chlorodisilane (3). Nonenolizable acid chlorides react variously with 1: Heptafluorobutyryl chloride gives t he [2+2] cycloaddition product, 11; trimethylacetyl chloride undergoes a slow reaction to give 3 and iso-butene; 3,4,5-trimethoxylbenzoyl ch loride produces 25% of a [2+4] cycloaddition product, 14. The X-ray cr ystal structure of 4b was determined: triclinic, P1, Z = 2, with cell dimensions a = 10.442(2) angstrom, b = 11.123(2) angstrom, c = 16.124( 3) angstrom, alpha = 78.06(3)-degrees, beta = 87.93(3)-degrees, and ga mma = 72.94(3)-degrees.