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Ring Expansion to 1‐Bromo‐1‐alumacyclonona‐2,4,6,8‐tetraene by Insertion of Two Alkyne Molecules into the AlC Bonds
Author(s) -
Agou Tomohiro,
Wasano Tatsuya,
Sasamori Takahiro,
Guo JingDong,
Nagase Shigeru,
Tokitoh Norihiro
Publication year - 2015
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201504468
Subject(s) - chemistry , ring (chemistry) , insertion reaction , dimer , alkyne , molecule , stereochemistry , crystallography , catalysis , organic chemistry
Treatment of 1‐bromo‐2,3,4,5‐tetraethylalumole ( 1 ) with 3‐hexyne afforded the corresponding product 1‐bromo‐1‐alumacyclonona‐2,4,6,8‐tetraene ( 2 ), accompanied by the formation of hexaethylbenzene. In the crystalline state, 2 forms a Br‐bridged dimer with a pseudo C 2 ‐symmetric and twisted AlC 8 nine‐membered ring. Deuterium‐labeling experiments and DFT calculations on the reaction of 1 with 3‐hexyne suggested that 1‐bromo‐1‐alumacyclohepta‐2,4,6‐triene, which is formed by the insertion of one molecule of 1‐hexyne into the AlC bond of alumole 1 , is the key intermediate for the generation of 2 as well as hexaethylbenzene.