CHEMISTRY OF CONVERSIONS OF O-1-(P-TOLYLSULFONYL)ALKYL]BENZYL]TRIMETHYLSILANES TO O-QUINODIMETHANES AND BENZOCYCLOBUTENES

thyl[o-[bromo(p-tolylsulfonyl)methyl]benyzl]silane (10) is prepared fr om o-[(trimethylsilyl)methyl]benzyl p-tolyl sulfone (9), n-BuLi, and b romine. Sulfone 9 eliminates trimethylsilyl bromide upon reaction with TBAF in acetonitrile to give the presumed intermediate, alpha-sulfony l-o-quinodimethane 11, which (1) dimerizes to disulfone 12 and (2) is trapped by alkyl fumarates to yield (p-tolylsulfonyl)tetrahydronaphtha lenes 17a,b and 18a,b, respectively. Sulfone 9 is converted by n-BuLi and alkyl halides to alpha-alkyl-alpha-bromosulfones 19a-f which react with TBAF to give alpha-sulfonylbenzocyclobutenes 21a-f and vinyl sul fones 23a-f, apparently upon ring closure and upon 1,5-sigmatropic rea rrangements of hydrogen in alpha-sulfonyl-o-quinodimethane intermediat es 20a-f and 22a-f. Further, sulfone 9, n-BuLi, and tert-butyl hypochl orite yield alpha-chlorosulfone 26 and alpha,alpha-dichlorosulfone 27. TBAF effects dechlorotrimethylsilation of 27 to chloro(p-tolylsulfony l)cyclobutene 28 presumably upon formation and cyclization of o-quinod imethane 29. Silanes 10, 19a-f, and 27 are therefore practical synthon s for o-quinodimethane intermediates 11, 20a-f and 22a-f, and 29 respe ctively.