Synthesis of 1,2-annulated and 1,2-unsubstituted pyrrolo[2,1,5-de]quinolizin-5-ones (cycl[3.3.2]azin-5-ones) via [3+2] cycloadditions of 1-oxoquinolizinium ylides with cyclic alkenes.
Org Biomol Chem
; 8(21): 4921-6, 2010 Nov 07.
Article
in En
| MEDLINE
| ID: mdl-20740245
ABSTRACT
1,2-Annulated pyrrolo[2,1,5-de]quinolizin-5-ones (cycl[3.3.2]azin-5-ones) 6a-6k, 8a-8b and 9 have been synthesized by one pot tandem reactions of 2-acetyl-N-phenacylpyridinium bromides (1a-1d) with electron-deficient cyclic alkenes (N-alkyl(aryl)maleimides, benzoquinones and naphthoquinone) in the presence of sodium carbonate as a base and tetrakispyridinecobalt(II) dichromate (TPCD) as an oxidant. These products are formed by 1.3-dipolar cycloaddition of the 1-oxoquinolizinium ylides generated in situ from 1a-1d with the alkene followed by dehydrogenation of the primary cycloadduct under the action of TPCD. Similar reactions of the ylides generated in situ from 1a-1f with maleic anhydride gave the 1,2-unsubstituted pyrrolo[2,1,5-de]quinolizin-5-ones 7a-7f via oxidative bisdecarboxylation and dehydrogenation of the primary cycloadducts under the action of TPCD.
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Database:
MEDLINE
Language:
En
Journal:
Org Biomol Chem
Journal subject:
BIOQUIMICA
/
QUIMICA
Year:
2010
Type:
Article