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Knorr-Rabe partial reduction of pyrroles: Application to the synthesis of indolizidine alkaloids

journal contribution
posted on 2023-05-16, 23:11 authored by Gourlay, BS, Ryan, JH, Jason SmithJason Smith
Background. The Birch reduction of electron rich pyrroles does not occur readily. However, dissolving metal reduction with zinc under acidic conditions gives 3-pyrrolines (2,5-dihydropyrroles) in reasonable yield. This dissolving metal reduction was first reported by Knorr and Rabe in 1901 but since then has only been reported for the reduction of electron rich pyrroles. Results. The partial reduction of bicyclic -ketopyrrole derivatives has been performed under dissolving metal conditions with zinc and hydrochloric acid to give excellent yields of hexahydroindolizidines. This reduction method has been utilised for the diastereoselective synthesis of 5-alkylindolizidines and the stereoselectivity obtained is opposite to that of catalytic hydrogenation. Conclusion. An efficient stereoselective synthesis of indolizidine alkaloids has been developed from -ketopyrrole intermediates using a modified version of Knorr and Rabe's pyrrole reduction. © 2008 Gourlay et al; licensee Beilstein-Institut.

History

Publication title

Beilstein Journal of Organic Chemistry

Volume

4

Pagination

EJ

ISSN

1860-5397

Department/School

School of Natural Sciences

Publisher

Beilstein Institut

Place of publication

Frankfurt

Repository Status

  • Restricted

Socio-economic Objectives

Expanding knowledge in the chemical sciences

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