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Preparation of new pyrido[3,4-b]thienopyrroles and pyrido[4,3-e]thienopyridazines
- Source :
-
Tetrahedron . Aug2008, Vol. 64 Issue 32, p7626-7632. 7p. - Publication Year :
- 2008
-
Abstract
- Abstract: Two new types of pyrido-fused tris-heterocycles (1a,b and 2a,b) have been prepared from 3-aminopyridine in five/six steps. A synthetic strategy for the preparation of the novel pyrido[3,4-b]thieno[2,3- and 3,2-d]pyrroles (1a,b) and pyrido[4,3-e]thieno[2,3- and 3,2-c]pyridazines (2a,b) has been studied. The Suzuki cross coupling of the appropriate 2- and 3-thienoboronic acids (3,4) and 4-bromo-3-pyridylpivaloylamide (9) afforded the biaryl coupling products (10,11) in high yields (85%). Diazotization of the hydrolysed (2-thienyl)-coupling product (12) and azide substitution gave the 3-azido-4-(2-thienyl)pyridine intermediate (72%, 14). 3-Azido-4-(3-thienyl)pyridine (15) was prepared by exchanging the previous order of reactions. The desired β-carboline thiophene analogues (1a,b) were obtained via the nitrene by thermal decomposition of the azido precursors (14,15). By optimising conditions for intramolecular diazocoupling, the corresponding pyridazine products (72–83%, 2a,b) were afforded. [Copyright &y& Elsevier]
- Subjects :
- *ORGANONITROGEN compounds
*PYRIDINE
*PYRROLES
*DIHYDROPYRIDINE
Subjects
Details
- Language :
- English
- ISSN :
- 00404020
- Volume :
- 64
- Issue :
- 32
- Database :
- Academic Search Index
- Journal :
- Tetrahedron
- Publication Type :
- Academic Journal
- Accession number :
- 32842898
- Full Text :
- https://doi.org/10.1016/j.tet.2008.05.062