Synthetic approaches to the naphthyl-isoquinoline alkaloids. Part 2.1 the total synthesis of (–)-0-methylancistrocladine and ( )-0-methylhamatine and their enantiomers2

Abstract

An asymmetric total synthesis of the naphthyl-isoquinoline alkaloids (–)-O-methylancistrocladine 39 is described; the synthetic method also provides routes to the atropisomer (+)-O-methylhamatine 43 and the enantiomers of these alkaloids. The asymmetric construction of the biaryl linkage involved the reaction of the Grignard reagent derived from 2-(2-bromo-3,5-dimethoxyphenyl)-1,3- dioxane 7 with (+)-(4S,5S)-4-(methoxymethyl)-5-phenyl-2-(1,4,5-trimethoxy-2-naphthyl)-4,5- dihydrooxazole 5. © 1991 by the Royal Society of Chemistry.