A Convenient Method for the Selective Alkylation ofβ-OH Groups of 2(3)-Hydroxyjuglones and Hydroxynaphthazarines

Abstract

Trimethyl-and triethylorthoformates have been used for the selective alkylation of β-OH groups of 2(3)-hydroxy-3(2)-alkyljuglones, 2-hydroxy-3-alkyl-, 2-hydroxy-3-chloro-, and 2,3-dihydroxynaphthazarines (1a-o,3,4). In most cases the corresponding alkoxy compounds (2a-q,5,6) were obtained in good yields. However, when 2-hydroxynaphthazarine (1p) was used, the formation of monomethineoxonol derivative (9) as the principal product took place.