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Synthesis of 1,2‐five‐ring‐annellated barrelenes via the intramolecular Diels ‐ Alder reaction of acetylenic derivatives
Author(s) -
Trifonov Latchezar S.,
Orahovats Alexander S.
Publication year - 1987
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19870700708
Subject(s) - chemistry , intramolecular force , diels–alder reaction , isocyanate , ring (chemistry) , cleavage (geology) , intramolecular reaction , medicinal chemistry , stereochemistry , organic chemistry , catalysis , geotechnical engineering , fracture (geology) , engineering , polyurethane
The intramolecular Diels‐Alder reaction conducted with acetylenic acylureas, obtained from carbodiimides, and the acetylenic acid 5 and its derivatives 13 gave the 1,2‐annellated barrelene 14 (from 13a ) and the benzobarrelenes 8 (from 5 ) and 15 (from 13b ); in the case of 3‐butynoic acid ( 1 ),[1,3]‐H shift were observed. The formation of the azabarrelenes 16 (from 13c ) as an intermediate is postulated which looses HCN to afford the indolinone 17 . The acylureas 6 and 9 underwent isocyanate cleavage instead of [4+2] cyclization.