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Synthesis of 1‐(4‐thiazolyl)azulenes: Reactions of bromoacetyl‐substituted azulenes with thioamides, thioureas, and thiosemicarbazones
Author(s) -
Takao Hiromi,
Wang DaoLin,
Kikuchi Shigeru,
Imafuku Kimiaki
Publication year - 2004
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.5570410512
Subject(s) - azulene , chemistry , yield (engineering) , medicinal chemistry , boiling , thiourea , organic chemistry , metallurgy , materials science
1‐(Bromoacetyl)‐3‐methylazulene (1a) and methyl 3‐(bromoacetyl)azulene‐1‐carboxylate (1b) reacted with thioamides 3a,b and thioureas 3c,d in boiling ethanol to give the corresponding (4‐thiazolyl)azulenes 4a‐d and 5a‐d in good yields, respectively. The reactions of dibromoacetyl‐substituted azulene (2) also gave (4‐thiazolyl) azulenes 5a‐d in lower yields and the azulene 2 was recovered. By heating compounds 5a‐d in 100% phosphoric acid, the ester group was eliminated to yield 1‐(4‐thiazolyl)azulenes 6a‐d. Compounds 1a,b reacted with thiosemicarbazones 7a‐f to afford [(2‐alkylidenehydrazino)thiazol‐4‐yl]azulenes 8a‐f and 9a‐f in moderate to high yields via their hydromides.