REACTIONS WITH TWOFOLD BRIDGED SULFONE-SUBSTITUTED DEWAR BENZENES - PREPARATION OF NEW DEWAR BENZENE-DERIVATIVES

The twofold bridged sulfone-substituted Dewar benzenes racyclo[7.5.2.0 (1,9).0(2,8)]hexadeca-2(8),15-diene (7a), acyclo[8.6.2.0(1,10).0(2,9)] octadeca-2(9),17-diene (7b), l)-1,4,5,6-tetramethylbicyclo[2.2.0]hexa- 2,5-diene (11), and racyclo[7.5.2.0(1,9).0(2,8)]hexadeca-2(8),15-diene (13a) were treated with SmI2, methyllithium, phenyllithium, and methy l, phenyl, and benzyl Grignard reagents, respectively. In the case of the reduction with SmI2 one tert-butylsulfonyl substituent (7a, 7b, 11 ) and the phenylsulfonyl group in 13a could be removed. Compound 7a re acts with methyllithium and phenyllithium with replacement of one RSO( 2) substituent by the alkyl or aryl group, respectively. With methyl a nd benzyl-magnesium bromide both RSO(2) groups in 7a could be replaced . The reaction of 7a with phenylmagnesium bromide leads to the mono- a nd disubstituted products and in addition to dimers of substituted phe nyl Dewar benzenes. For the reaction with organolithium and Grignard c ompounds there are indications of a SET mechanism. The X-ray structure s of tracyclo[7.5.2.0(1,9).0(2,8)]hexadeca-2(8)15-diene (32a) and the corresponding dibenzyl derivative 834a) were investigated by using sin gle crystals.