2,5-Dimethoxypropenylbenzene from ß-Asarone
Cis-beta-asarone to trans-alpha-asarone
A mixture of cis-beta-asarone (70 g) alcohol (100 ml) and selenium dioxide (10 g) was heated on the water-bath for 30 min. The filtered solution was poured into water, the oil dissolved in ether, and the dried etheral extract evaporated; the residue partly crystallized, and distillation gave trans-alpha-asarone (60g).
Cis-beta-asarone to 2,5-dimethoxypropenylbenzene
A mixture of ß-asarone (20g), alcohol (50 ml) and selenium dioxide (5 g) was boiled for 5 hours. The product isloated by ether in the usual manner gave an oil, which on distillation under 8 mmHg gave two fractions: (i) bp 140-145º, d30º/30º 1.052, n20º/d 1.5451; (ii) bp 145-150º.
From the former, a picrate was prepared, crystallizing from alcohol in orange-red feathery leaflets, mp 87º. Decomposition of the picrate with alkali gave 2,5-dimethoxypropenylbenzene, bp 128-129º/4 mm., d30º/30º 1.041, n30º/d 1.5548. The 2,5-dimethoxypropenylbenzene pseudonitrosite, mp 118º, was a pale yellow powder.
References
[1] Rao & Subramaniam, Journal of the Chemical Society 1338 (1937)
