Stereoselective synthesis of dihydrothiadiazinoazines and dihydrothiadiazinoazoles and their pyrolytic desulfurization ring contraction

被引：23
作者：
Al-Etaibi, Alya [2 ]
John, Elizabeth [1 ]
Ibrahim, Maher R. [1 ]
Al-Awadi, Nouria A. [1 ]
Ibrahim, Yehia A. [1 ]
机构：
[1] Kuwait Univ, Fac Sci, Dept Chem, Safat 13060, Kuwait
[2] Publ Author Appl Educ & Training, Coll Hlth Sci, Dept Nat Sci, Kuwait, Kuwait
来源：
TETRAHEDRON | 2011年 / 67卷 / 34期
关键词：
Pyrolysis; Stereoselective synthesis; 1,2,4]Triazolo[3,4-b][1,3,4]thiadiazines; 1,2,4]Triazino[3,4-b][1,3,4]thiadiazin-4-ones; 1,3,4]Thiadiazino[2,3-b]quinazolin-10-ones; Pyrazolo[5,1-b][1,2,4]triazoles; Pyrazolo[5,1-c][1,2,4]triazin-4-ones; Pyrazolo[4,3-b]quinazolin-9-ones; GAS-PHASE THERMOLYSIS; CARBONATE PYROLYSIS; INTERESTING ROUTES; SCHIFF-BASES; CYCLIZATION; SYSTEMS;
D O I：
10.1016/j.tet.2011.06.034
中图分类号：
O62 [有机化学];
学科分类号：
070303 ; 081704 ;
摘要：
Intramolecular base catalyzed C-C bond formation led to exclusive stereoselective syntheses of trans-6,7-dihydro-5H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazines, trans-7,8-dihydro-6H-[1,2,4]triazino[3,4-b] [1,3,4]thiadiazin-4-ones, and trans-3,4-dihydro-2H-[1,3,4]thiadiazino[2,3-b]quinazolin-10-one. trans-6,7-Dihydro-5H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazines isomerize slowly in CDCl(3) and more rapidly in DMSO-d(6) into the corresponding cis-stereoisomers. The other trans-6,7-dihydro-1 1,3,4]thiadiazines isomerize also in DMSO-d6 into the corresponding cis-stereoisomers. Pyrolytic conversion of these heterocyclic condensed dihydrothiadiazines into their corresponding pyrazolo[5,1-b][1,2,4]triazoles, pyrazolo[5,1-c][1,2,4]triazin-4-ones and pyrazolo[4,3-b]quinazolin-9-ones via desulfurization ring contraction is described. (C) 2011 Elsevier Ltd. All rights reserved.
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页码：6259 / 6274
页数：16
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