Pyridinols protégés et leur utilisation en métallation. Synthèse d'indolizidines à partir de la pyridine : synthèse d'indolizidines à partir de la pyridine

Abstract : We report that the tetrahydropyranylation of pyridinols and phenols, exhibiting especially very low nucleophilicities, can be achieved by means of Mitsunobu reaction with 2-hydroxy-tetrahydropyran. We studied the regioselective deprotonation of 3- an 4-(tetrahdropyran-2-yloxy)pyridines with n-butyllithium. Trapping the lithiated species with various electrophiles afforded functionalized pyridines in good yields. A one-pot procedure also allowed the double fuctionalization at C4 and C2 in the case of 3-O-THP-pyridine. The ortho-metallating ability of this group was examined in comparison with other well-known oxygen-based ortho-directing groups. A four-step synthesis of (-)-lentiginosine and its epimers is described starting from 2-bromopyridine. The key step consisted of a quaternarization of a fully unprotected pyridinium-polyol unit using Mitsunobu methodology. We have demonstrated that the Mitsunobu reaction is viable as a new methodology for the N-alkylation of pyridine and for the formation of bridgehead azabicyclic compounds from pyridine derivatives
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Chemical Sciences. INSA de Rouen, 2008. French. <NNT : 2008ISAM0004>


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Rabah Azzouz. Pyridinols protégés et leur utilisation en métallation. Synthèse d'indolizidines à partir de la pyridine : synthèse d'indolizidines à partir de la pyridine. Chemical Sciences. INSA de Rouen, 2008. French. <NNT : 2008ISAM0004>. <tel-00559656>

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