Rearrangaments of Azabiphenylenes. The Impact of Nitrogen Number and Position

Article abstract of DOI:10.1021/jo00214a012

4-Methoxy-1-azabiphenylene and 1-methoxy-2-azabiphenylene have been synthesized from the appropriate precursor diethynylmethoxypyridines via cobalt-catalyzed cooligomerization with bis(trimethylsilyl)acetylene.When 4-methoxy-1,3-diazabiphenylene was transformed into 1,3-dimethoxyisoquinoline in methanolic sodium methoxide at reflux overnight, 1-methoxy-2-azabiphenylene required longer reflux time and 4-methoxy-1-azabiphenylene required forcing conditions for transformations to occur.The transformations product from the latter was shown to be 1,5-dimethoxy-2-benzazocine and that from the former was established by independent synthesis to be 3-methoxy-1-((E)-2-methoxyethenyl)isoquinoline.The impressive disparity in the products obtained from the methoxydiazabiphenylene and the two methoxyazabiphenylenes can be rationalized by consideration of the locus of methanol addition and sequential electrocyclic reactions.