IMDAF Cycloaddition as a Method for the Preparation of Pyrrolophenanthridine Alkaloids

A Padwa, M Dimitroff, AG Waterson…

Index: Padwa, Albert; Dimitroff, Martin; Waterson, Alex G.; Wu, Tianhua Journal of Organic Chemistry, 1998 , vol. 63, # 12 p. 3986 - 3997

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Citation Number: 78

Abstract

Acylation of 5-amino-2-furancarboxylic acid methyl ester with alkenoyl acid chlorides gives 2- amidofurans that undergo intramolecular Diels-Alder cycloadditions. The reactions occur at 165° C in toluene or at 100° C when 4 M ethereal LiClO4 was used as the solvent. The resultant dihydroindoles are formed by the nitrogen lone pair assisted ring opening of the initial oxa-bridged cycloadducts, followed by loss of water. Under certain conditions, ...