Intramolecular Cyclization of β-Amino and β-Ammonio Radicals: A New Synthetic Route to the 1-Azabicyclo[3.2.1]octyl- and -[2.2.1]heptyl Systems
| Autor: | Paul A. Smith, Ernest W. Della |
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| Rok vydání: | 2000 |
| Předmět: | |
| Zdroj: | The Journal of Organic Chemistry. 65:6627-6633 |
| ISSN: | 1520-6904 0022-3263 |
| DOI: | 10.1021/jo000790v |
| Popis: | Treatment of 1-(2-phenylselenoethyl)-1,2,5,6-tetrahydropyridine (15) with tributyltin hydride affords only the product of reduction, demonstrating the reluctance of the 5-hexenyl radical 9 to undergo ring closure. When the nature of the radical is modified, either by introduction of an ester group at C4 or via its quaternary ammonium salt, cyclization occurs readily; while the radical 52 gives an excellent yield of 1-methyl-1-azoniabicyclo[3.2.1.]octyl bromide (55) uncontaminated with the product of reduction, the bicyclic product from 21 is accompanied by some reduced material. Production of the unwanted alkene can be eliminated in the latter by recourse to the quaternary ammonium ester 1-(2-bromoethyl)-4-carbethoxy-1-methyl-1,2,5,6-tetrahydropyridinium bromide (35) which, when exposed to tributyltin hydride, affords a 1:1 endo/exo mixture of 4-carbethoxy-1-methyl-1-azoniabicyclo[3.2.1]octyl bromide (37) exclusively. These results support the demonstration of the powerful polar effect of an ester functio... |
| Databáze: | OpenAIRE |
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