Stereocontrolled Annulations of Indolo[2,3-a]quinolizidine-Derived Lactams with a Silylated Nazarov Reagent: Access to Allo and Epiallo Yohimbine-Type Derivatives

Chemistry : a European Journal
Federica ArioliMercedes Amat

Abstract

The facial selectivity of double Michael addition reactions of the silylated Nazarov reagent 4 to unsaturated indolo[2,3-a]quinolizidine lactams 3 has been studied. Pentacyclic 3-H/15-H trans adducts 5 are generated from Nind -unsubstituted lactams, but the corresponding cis isomers 6 are formed when the indole nitrogen has a tert-butyloxycarbonyl (Boc) substituent. This reversal in the facial selectivity of the annulation has been rationalized by means of theoretical calculations, which indicate that the initial nucleophilic attack under stereoelectronic control is hampered by the presence of the bulky Boc group. The synthetic usefulness of the pentacyclic Nazarov-derived adducts is demonstrated by their conversion into allo and epiallo yohimbine-type targets.

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Jul 16, 2014·The Journal of Organic Chemistry·Federica ArioliMercedes Amat

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Citations

Feb 6, 2019·Molecules : a Journal of Synthetic Chemistry and Natural Product Chemistry·Federica ArioliMercedes Amat
Aug 12, 2016·Molecules : a Journal of Synthetic Chemistry and Natural Product Chemistry·Nuno A L PereiraMaria M M Santos

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