The Stobbe condensation. Part IV. The cyclisation of 3-methoxycarbonyl-cis-4-(1- and 2-naphthyl)but-3-enoic acids into the corresponding phenanthrene derivatives, and of 3-methoxycarbonyl-cis-4-(5,6,7,8-tetrahydro-2-naphthyl)but-3-enoic acid into the corresponding isomeric phenanthrene and anthracene derivatives

Abstract

3-Methoxycarbonyl-cis-4-(1- and 2-naphthyl)but-3-enoic acids (I and II) are cyclised by acetic anhydride and sodium acetate to methyl 1-acetoxyphenanthrene-3-carboxylate and methyl 4-acetoxy-phenanthrene-2-carboxylate, which may be converted into 1-methoxy- and 4-methoxy-phenanthrene, respectively. However, a similar cyclisation of 3-methoxycarbonyl-cis-4-(5,6,7,8-tetrahydro-2-naphthyl)but-3-enoic acid gave a mixture of methyl 4-acetoxy-5,6,7,8-tetrahydrophenanthrene-2-carboxylate (predominant), and methyl 1-acetoxy-5,6,7,8-tetrahydroanthracene-3-carboxylate.

Alcoholysis of the cis-4-(1- and 2-naphthyl)but-3-en-1,3-dicarboxylic anhydrides yields the α-methoxycarbonylmethyl-trans-β-(1- and 2-naphthyl)acrylic acids, respectively, which are different from the half esters (I and II) obtained by the Stobbe condensation.