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Reactions with Twofold Bridged Sulfone‐Substituted Dewar Benzenes – Preparation of New Dewar Benzene Derivatives
Author(s) -
Ohlbach Frank,
Gleiter Rolf,
Oeser Thomas,
Irngartinger Hermann
Publication year - 1996
Publication title -
liebigs annalen
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0947-3440
DOI - 10.1002/jlac.199619960525
Subject(s) - methyllithium , phenyllithium , chemistry , substituent , medicinal chemistry , bromide , diene , sulfone , aryl , trimethylsilyl , stereochemistry , organic chemistry , alkyl , natural rubber
The twofold bridged sulfone‐substituted Dewar benzenes 15,16‐bis( tert ‐butylsulfonyl)tetracyclo[7.5.2.0 1,9 .0 2,8 ]hexadeca‐2(8),15‐diene ( 7a ), 17,18‐bis( tert ‐butylsulfonyl)tetracyclo[8.6.2.0 1,10 .0 2,9 ]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[7.5.2.0 1,9 .0 2,8 ]hexadeca‐2(8),15‐diene ( 13a ) were treated with SmI 2 , methyllithium, phenyllithium, and methyl, phenyl, and benzyl Grignard reagents, respectively. In the case of the reduction with SmI 2 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 RSO 2 substituent by the alkyl or aryl group, respectively. With methyl and benzylmagnesium bromide both RSO 2 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[7.5.2.0 1,9 .0 2,8 ]hexadeca‐2(8),15‐diene ( 32a ) and the corresponding dibenzyl derivative 8 34a ) were investigated by using single crystals.