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Addition of a Functionalized Isoprene Unit to an Allyl Alcohol. III. The reaction with optically active cis ‐carveol
Author(s) -
Thomas Alan F.,
Ohloff G.
Publication year - 1970
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.19700530530
Subject(s) - chemistry , diradical , isoprene , optically active , allyl alcohol , sigmatropic reaction , claisen rearrangement , chirality (physics) , diene , alcohol , medicinal chemistry , stereochemistry , organic chemistry , catalysis , singlet state , quantum chromodynamics , physics , chiral symmetry breaking , natural rubber , quantum mechanics , nuclear physics , nambu–jona lasinio model , copolymer , excited state , polymer
Provided the temperature is kept under 150°, diene ethers of allyl alcohols rearrange in the double Claisen ‐ Cope reaction largely by a sigmatropic process in both stages. This was demonstrated by using the 2‐methylbutadienyl ether of (−)‐ cis ‐carveol, when the product obtained after the two rearrangements was optically active. To check the extent of chirality loss, the same product was synthesized by a route involving only one sigmatropic reaction instead of two. When the reaction occurs at higher temperature, much more chirality is lost, corresponding to the intervention of a diradical process.