ISSN:
0018-019X
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The rearrangement of 10-allyl-2-oxo-Δ1(9), 3-hexahydronaphthalene (12) catalysed by trifluoroacetic acid and other Bronsted acids yielded almost exclusively the [3s, 3s]-products, 1- and 3-allyl-5,6,7,8-tetrahydro-2-naphthol (16 and 15, respectively). The rearrangement of 12 with trifluoroacetic anhydride or acetic anhydride/sulfuric acid, yields, besides 15 and 16, appreciable amounts of the [1s, 2s]-rearrangement product, 4-allyl-5,6,7,8-tetrahydro-2-naphthol (14) (table 1).The CF3COOH catalysed dienone-phenol-rearrangement of 6-ally-5,6-dimethyl-cyclohexa-2,4-dien-l-one (11) in hexane at 0° yields4-allyl-2,3-dimethyl-phenol (19). Rearrangement of d3-ll containing a specifically deuteriated allyl group proves that the formation of d3-19 occurs via a [3s, 3s]-sigmatropic reaction. On the other hand, treatment of 11 with (CF3CO)2O at 0° in hexane gives (after saponification) 4-allyl-, 5-allyl- and 6-allyl-2,3-dimethyl-phenol (19, 20 and 21, respectivcly). This reaction occurs via an acyloxybenzenium-ion intermediate. The reactions performed with d3-11 demonstrate that the formation of d3-19 occurs both by a direct [3s, 3s]-shift and by a twofold [1s, 2s]-shift, respectively. d3-20 is formcd by a [3s, 4s]-sigmatropic reaction. d3-21 is obtained with about 95% inversion of the carbon skeleton of the allyl group. Thus d3-21 is mainly formed by a [1s, 2s]- followed by a [3s, 4s]-sigmatropic rearrangement.6-Allyl-6-niethyl-cyclohexa-2,4-dien-1-one (4) yields with CF3COOH in hexane 4-allyl-2-methyl-phenol (5), whereas with (CF3CO)2O in hexane 5, 3-allyl- and 5-allyl-2-methyl-phenol (24 and 25, respectively) are formed in comparable amounts. As a minor product 6-allyl-2-methyl-phenol (26) was observed.Based on these observations, the concept of charge-induced, e.g. schemes 2 and 3, and charge-controlled, e.g. scheme 7, sigmatropic reactions, has been elaborated. In the former, the charge serves only to accelerate appreciably thermal orbital-symmetry allowed reactions, whereas in the latter, the charge determines the course of the transformations according to the Woodward-Hoffmann rules.Especially in acetylating systems, allylcyclohexdienones undergo charge-induced and charge-controlled reactions simultaneously.
Additional Material:
4 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/hlca.19730560104
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