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Stereospecific, R 2 AlCl‐Promoted Intramolecular Ene Reaction of a 1,6‐Dienoate: Evidence for a Concerted Mechanism
Author(s) -
Oppolzer Wolfgang,
Mirza Sohail
Publication year - 1984
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.19840670312
Subject(s) - chemistry , ene reaction , stereospecificity , concerted reaction , intramolecular force , yield (engineering) , stereochemistry , methylene , reaction mechanism , medicinal chemistry , organic chemistry , catalysis , materials science , metallurgy
Treatment of the 83%‐ trans ‐ 13 CH 3 ‐labelled 1,6‐dienoate 7 with Et 2 AlCl at–78° provided in high yield the ene product 9 containing 83% 13 C localized in the olefinic C(8)‐methylene group. Accordingly, H‐transfer occurs exclusively from the trans ‐methyl group of 7 , consistent with a concerted ene process 7 9 thereby ruling out an intermediate cation 8 ( Scheme 4 ).