Topic
Intramolecular reaction
About: Intramolecular reaction is a research topic. Over the lifetime, 5015 publications have been published within this topic receiving 138213 citations.
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TL;DR: In this article, a new approach for asymmetric construction of the pyrrolo[2,3,i]-isoquinoline core of manzamine A is described, which starts with D-(−)-quinic acid and features an intramolecular Mannich reaction as the central step.
42 citations
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TL;DR: Conversion of N-hydroxytryptamines en derives N-alkoxy par protections successives avec le [2-(trimethysilyl)ethyl]chloroformate, reaction avec des sulfures de chloromethyle fonctionnalises and deprotection avec un florure.
Abstract: Conversion de N-hydroxytryptamines en derives N-alkoxy par protections successives avec le [2-(trimethysilyl)ethyl]chloroformate, reaction avec des sulfures de chloromethyle fonctionnalises et deprotection avec un florure. Cyclisation intramoleculaire, reduction du methyle ester par le DIBAL et traitement par le TFA pour obtenir la paire de diastereoisomeres (eudistomine) avec une legere selectivite pour l'isomere trans (cis/trans∼35/65)
42 citations
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TL;DR: Observations confirmed that the epimerization involves an acyclic alpha,beta-unsaturated aldehyde or ketone, which is formed by the enolation of 2'-carbonyl-alpha-C-glycoside with subsequent beta-elimination.
Abstract: Treatment of 2'-carbonyl-alpha-C-glycopyranosides of gluco, galacto, manno, 2-deoxy, and 2-azido sugars with 4% NaOMe resulted in anomeric epimerization to give their respective beta-anomers in good to excellent yields. The epimerization of the 2'-aldehyde of alpha-C-galactopyranoside (10) in deuterium methanol, which afforded the beta-anomer with exclusive deuterium replacements at the 1'-position, excluded the possibility of the exo-glycal as being involved as an intermediate. When 2'-aldehyde (36) and 2'-ketone (41) of 2,3-di-O-benzyl-alpha/beta-l-C-arabinofuranoside were used as substrates we were able to obtain the respective equatorial alpha-C-arabinopyranosides (37 and 42). These observations confirmed that the epimerization involves an acyclic alpha,beta-unsaturated aldehyde or ketone, which is formed by the enolation of 2'-carbonyl-alpha-C-glycoside with subsequent beta-elimination. Thereafter an intramolecular hetero-Michael cycloaddition occurs, leading to the formation of thermodynamically controlled stable products, which were exclusively the equatorial C-glycopyranosides, except in the case of 2'-carbonyl-C-furanosides, where a mixture of two anomers was obtained.
42 citations
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TL;DR: Asymmetric induction has been achieved in the intramolecular Pauson-Khand reaction of 7-alkoxy-1-hepten-6-ynes derived from chiral alcohols as discussed by the authors.
42 citations
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TL;DR: Remote intramolecular hydrogen bonds (HBs) in phenols and benzylammonium cations influence the dissociation enthalpies of their O-H and C-N bonds, respectively, which are reflected in the transition states for, and hence in the kinetics of, hydrogen atom abstraction from phenols by free radicals.
Abstract: Remote intramolecular hydrogen bonds (HBs) in phenols and benzylammonium cations influence the dissociation enthalpies of their O−H and C−N bonds, respectively. The direction of these intramolecula...
42 citations