Premium
Synthesis of phenaleno[1,9‐ bc ]thiophene
Author(s) -
Tominaga Yoshinori,
Lee Milton L.,
Castle Raymond N.
Publication year - 1981
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570180526
Subject(s) - thiophene , chemistry , yield (engineering) , potassium hydroxide , sodium hydroxide , halogenation , acetone , medicinal chemistry , aldehyde , organic chemistry , sodium cyanide , nuclear chemistry , cyanide , catalysis , materials science , metallurgy
The cyclization of 2‐acetonylthionaphthalene, prepared from 2‐mercaptonaphthalene (1) and chloro‐acetone in the presence of sodium hydroxide, with polyphosphoric acid gave 1‐methylnaphtho[2,1‐ b ]thiophene (4) in 64% overall yield from 1. By bromination with N ‐bromosuccinimide, 4 was converted in 40% yield into l‐bromomethylnaphtho[2,1‐ b ]thiophene (8) . Treatment of 8 with potassium cyanide in a phase‐transfer medium gave l‐cyanomethylnaphtho[2,1‐ b ]thiophene (10) in good yield. Compound 10 was reduced to the corresponding aldehyde 11 and then cyclized with polyphosphoric acid to phenaleno[l,9‐ bc ]thiophene (12) in 24% overall yield from 10.