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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:
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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