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Reactions of Cyclic Diynes with Acceptor‐Substituted Alkynes: Syntheses of Doubly Bridged Dewar Benzenes
Author(s) -
Gleiter Rolf,
Ohlbach Frank,
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.199619960524
Subject(s) - chemistry , dimethyl acetylenedicarboxylate , acetylene , benzene , yield (engineering) , medicinal chemistry , derivative (finance) , steric effects , ring (chemistry) , stereochemistry , cycloaddition , organic chemistry , catalysis , economics , metallurgy , materials science , financial economics
The reaction of the AlCl 3 complex of cyclic diynes (mainly a 14‐membered ring) with dimethyl acetylenedicarboxylate (DMAD) or bis( tert ‐butylsulfonyl)acetylene (BTSA) and related compounds was investigated. The reaction of the AlCl 3 complex of cyclotetradeca‐1,8‐diyne ( 1 , n = 5) with DMAD affords in 60% yield two isomers in a ratio of 7:3. The isomers were identified as the 1,4‐ and 2,3‐bridged Dewar benzene derivative A and the 1,2‐ and 3,4‐bridged Dewar benzene derivative B . Acetylenes with sterically more demanding groups such as BTSA or bis(diphenylphosphanyl)acetylene P , P ′‐dioxide (BDPA) yield only the isomer A . The X‐ray structures of the cycloadduct between 1 ( n = 5 and 6) and BTSA, as well as of 2,3‐bis( tert ‐butylsulfonyl)‐1,4,5,6‐tetramethylbicyclo[2.2.0]hexa‐2,5‐diene ( 31 ) are described. The mechanism of the cycloadditions is discussed.