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Reactions of [2‐(2‐Naphthyl)phenyl]acetylenes and 2‐(2‐Naphthyl)benzaldehyde O ‐Phenyloximes: Synthesis of the Angucycline Tetrangulol and 1,10,12‐Trimethoxy‐8‐methylbenzo[ c ]phenanthridine
Author(s) -
Ngwira Kennedy J.,
Rousseau Amanda L.,
Johnson Myron M.,
de Koning Charles B.
Publication year - 2017
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201601373
Subject(s) - benzaldehyde , chemistry , phenanthridine , medicinal chemistry , alkyne , catalysis , organic chemistry
The Suzuki–Miyaura coupling reaction between (1,4,5‐trimethoxynaphthalen‐2‐yl)boronic acid and 2‐iodo‐3‐methoxy‐5‐methylbenzaldehyde gave the intermediate 3‐methoxy‐5‐methyl‐2‐(1,4,5‐trimethoxynaphthalen‐2‐yl)benzaldehyde. Conversion of this benzaldehyde into the alkyne 2‐(2‐ethynyl‐6‐methoxy‐4‐methylphenyl)‐1,4,5‐trimethoxynaphthalene was accomplished through a Corey–Fuchs reaction. Exposure of the derived acetylene to a catalytic platinum(II)‐mediated ring closure gave the required tetracyclic aromatic product, 1,7,8,12‐tetramethoxy‐3‐methyltetraphene, which was then converted into tetrangulol. Exposure of the related 3‐methoxy‐5‐methyl‐2‐(1,4,5‐trimethoxynaphthalen‐2‐yl)benzaldehyde O ‐phenyloxime to microwave irradiation in an ionic liquid yielded 1,10,12‐trimethoxy‐8‐methylbenzo[ c ]phenanthridine, instead of the desired natural product phenanthroviridone.