Title:
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Origin of the Base-Dependent Facial Selectivity in Annulation Reactions of Nazarov-Type Reagents with Unsaturated Indolo[2,3-a] quinolizidine Lactams
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Author:
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Estarellas, Carolina; Arioli, Federica; Pérez Bosch, Maria; Are, Celeste; Hevia, David; Molins i Grau, Elies; Luque Garriga, F. Xavier; Bosch Cartes, Joan; Amat Tusón, Mercedes
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Other authors:
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Universitat de Barcelona |
Abstract:
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Methyl-substituted Nazarov reagent 4 reacts stereoselectively with N-ind-Boc indoloquinolizidine lactams to give the expected 3-H/15-H cis pentacyclic yohimbine-type adducts when using 1,8-diazabicyclo[5.4.0] undec-7-ene (DBU) as the base. However, a dramatic change of the facial selectivity was observed when the reaction was performed in the presence of Cs2CO3, leading to the corresponding trans adducts. This annulation is the key step of a stereocontrolled synthesis of the 17acarba analogue of the heteroyohimbine alkaloid akuammigine. Theoretical calculations were used to rationalize the facial selectivity of these double Michael addition reactions. |
Subject(s):
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-Teoria del funcional de densitat -Indicadors (Química) -Proves i reactius químics -Química orgànica -Density functionals -Indicators and test-papers -Chemical tests and reagents -Organic chemistry |
Rights:
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(c) Wiley-VCH, 2017
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Document type:
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Article Article - Accepted version |
Published by:
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Wiley-VCH
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