Reactions with Twofold Bridged Sulfone‐Substituted Dewar Benzenes – Preparation of New Dewar Benzene Derivatives

AbstractThe twofold bridged sulfone‐substituted Dewar benzenes 15,16‐bis(tert‐butylsulfonyl)tetracyclo[7.5.2.01,9.02,8]hexadeca‐2(8),15‐diene (7a), 17,18‐bis(tert‐butylsulfonyl)tetracyclo[8.6.2.01,10.02,9]octadeca‐2(9),17‐diene (7b), 2,3‐bis(tert‐butylsulfonyl)‐1,4,5,6‐tetramethylbicyclo[2.2.0]hexa‐2,5‐diene (11), and 15‐(phenylsulfonyl)‐16‐(trimethylsilyl)tetracyclo[7.5.2.01,9.02,8]hexadeca‐2(8),15‐diene (13a) were treated with SmI2, methyllithium, phenyllithium, and methyl, 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 reacts with methyllithium and phenyllithium with replacement of one RSO2 substituent by the alkyl or aryl group, respectively. With methyl and benzylmagnesium bromide both RSO2 groups in 7a could be replaced. The reaction of 7a with phenylmagnesium bromide leads to the mono‐ and disubstituted products and in addition to dimers of substituted phenyl Dewar benzenes. For the reaction with organolithium and Grignard compounds there are indications of a SET mechanism. The X‐ray structures of 15,16‐dimethyltetracyclo[7.5.2.01,9.02,8]hexadeca‐2(8),15‐diene (32a) and the corresponding dibenzyl derivative 834a) were investigated by using single crystals.