SILICON-COMPOUNDS WITH STRONG INTRAMOLECULAR STERIC INTERACTIONS .57.OXIDATION AND CYCLOADDITION REACTIONS OF AN UNSYMMETRICALLY SUBSTITUTED DISILENE

Reaction of the unsymmetrically substituted disilene R(2)Si= SiR'(2) ( 4; R= 2,4,6-Me(3)C(6)H(2), R' = 2,4,6-iPr(3)C(6)H(2)) with m-chloroper benzoic acid (mCPBA) or oxygen furnished the correspondingly substitut ed 1,2,3-oxadisilirane 5 or 1,3,2,4-di-oxadisiletane 6, respectively. The [2 + 2] and [2 + 4] cycloaddition reactions of 4 with benzophenone and 3,5-di-tert-buthyl-1,2-benzoquinone, respectively, proceeded with a high degree of regioselectivity to yield the 1,2,3-oxadisiletane 9 and the 2,3-dihydro-1,4,2,3-benzodioxadisiline 7. The latter product w as isolated together with a small amount of an isomeric compound 8 in which the substituents at the silicon atoms are reversed, The molecula r structures of the products 5, 6, and 7 were determined by X-ray crys tallography.