A Facile Synthesis of Angularly-Fused 3, 4, 4a, 10b-Tetrahydro-2H, 5H-pyrano[3, 2-c]benzopyrans by the One-pot Condensation between Salicylaldehydes and Unsaturated Alcohols [in Japanese]
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Salicylaldehydes reacted with 5-methyl-4-hexen-1-ol (<B>4a</B>) or 6-methyl-5-hepten-2-ol (<B>4b</B>) in benzene in the presence of trimethyl orthoformate and a catalytic amount of <I>p</I>-toluenesulfonic acid at rt to give angularly-fused <I>trans</I>-5,5-dimethyl-3,4,4a,10b-tetrahydro-2<I>H</I>,5<I>H</I>-pyrano[3,2-c]benzopyrans (<B>6</B>) in high yields with complete stereoselectivity.
- Chemistry Letters
Chemistry Letters 1996(10), 889-890, 1996-10
The Chemical Society of Japan