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Synthesis and Diazotization of Diethyl 6‐Amino‐2‐Hydroxyazulene‐1,3‐Dicarboxylate and Its 2‐Acetoxyl Derivative
Author(s) -
Huang TianChyuan,
Morita Tadayoshi,
Lin BingBing,
Lin YunShan
Publication year - 1994
Publication title -
journal of the chinese chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.329
H-Index - 45
eISSN - 2192-6549
pISSN - 0009-4536
DOI - 10.1002/jccs.199400029
Subject(s) - chemistry , diazo , derivative (finance) , sulfuric acid , acetic acid , sodium nitrite , azulene , zinc , medicinal chemistry , organic chemistry , financial economics , economics
Diethyl 6‐amino‐2‐hydroxyazulene‐1,3‐dicarboxylate ( 6a ) and 2‐acetoxyl derivative ( 6b ) were synthesized by reduction of the 6‐azido derivatives ( 5a,b ) with zinc/acetic acid in excellent yields. 5a and 5b were prepared by azidation of diethyl 2‐acetoxy‐6‐bromoazulene‐1,3‐dicarboxylate (4). Diazotization of 6a with sodium nitrite in the presence of concentrated sulfuric acid in dioxane gave diethyl 2‐hydroxy‐ ( 7a ), 2,6‐dihydroxy‐ ( 8a ), and 2‐hydroxy‐6‐[2‐(2‐hydroxyethoxy)ethoxy]‐azulene‐1,3‐dicarboxylates ( 9a ), in 5, 35 and 20% yields, respectively. Similar reaction of 6b gave the corresponding acetates 7b, 8b , and 9b , compounds of the same type from 6a . No evidence for the formation of 6‐diazo‐1,3‐diethoxycarbonyl‐2(6H) azulenone ( 2b ) was obtained in the employed reaction conditions.