Nucleophilic alkenes. VI. Addition of 1,1-dimethoxyethene to 1,2-naphthoquinones and 9,10-phenanthraquinones

Abstract

1,2-Naphthoquinone underwent 1 : 2-addition of 1,1-dimethoxyethene to give 1,3-dimethoxy-9,10-phenanthraquinone, a process having analogy in the 1,4-quinone series. 1,2-Naphthoquinonesand 9,10-phenanthraquinones also underwent direct attack at the carbonyl carbon. This latter process has no observed analogy in the 1,4-quinone series and presumably is assisted by unfavoured juxtaposition of the two carbonyl groups. Mixtures of products were generally obtained and five different reaction types were identified-vinylogous 1 : 1- and 1 : 2-addition, direct 1 : 1- and 1 : 2-addition, and dioxole formation through bridging of the carbonyl oxygens.