Novel Ag(I)-catalysis of an intramolecular 1,3-dipolar cycloaddition
作者:Andrew S. Kende、Michel Journet
DOI:10.1016/0040-4039(95)00470-w
日期:1995.5
Acetylenic α-diazoketones, bearing gem-dimethyl substituents in the α′ position, were found to undergo an intramolecular 1,3-dipolar cycloaddition reaction in the presence of silver(I) as catalyst. In that instance, bicyclic pyrazole derivatives were isolated in 47 to 55% yield, even in the conditions of the Arndt-Eistert reaction. The requirement for gem-dimethylsubstitution in acyclic substrates is rationalized
An improved synthesis of α,β-unsaturated nitrones relevant to the stephacidins and analogs thereof
作者:Benjamin D. Hafensteiner、María Escribano、Elena Petricci、Phil S. Baran
DOI:10.1016/j.bmcl.2009.04.045
日期:2009.7
A new method is reported for the synthesis of the α,β-unsaturated nitrone moiety characteristic of the stephacidin/avrainvillamide family of bioactive prenylatedindole alkaloids. Application to the synthesis of stephacidin analogs and a potential biological probe are showcased.
Synthetic and Theoretical Studies on Group-Transfer Imidoylation of Organotellurium Compounds. Remarkable Reactivity of Isonitriles in Comparison with Carbon Monoxide in Radical-Mediated Reactions
作者:Shigeru Yamago、Hiroshi Miyazoe、Ryuta Goto、Masahiro Hashidume、Takashi Sawazaki、Jun-ichi Yoshida
DOI:10.1021/ja003879r
日期:2001.4.1
Imidoylation of organotellurium compounds with isonitriles has been investigated in conjunction with the radical-mediated C1 homologation reaction by using CO and isonitriles. Carbon-centered radicals generated photochemically or thermally from organotellurium compounds react with isonitriles in a group-transfer manner to give the corresponding imidoylated products. Organotellurium compounds have been found to serve as effective precursors of a wide variety of stabilized radicals, namely benzyl, alpha -alkoxy, alpha -amino, and acyl radicals, which take part in the imidoylation with high efficiency. The reactions are compatible with various functional groups, and can be carried out in various solvents including environmentally benign water. The reactivity of isonitriles has been compared with that of CO through competition experiments, and the results indicate that isonitriles are superior to CO as radical accepters in reactions with stabilized radicals. The origin of the differences has been addressed in theoretical studies with density functional theory calculations using the B3LYP hybrid functional. The calculations suggest that both carbonylation and imidoylation proceed with low activation energies, and that there an virtually no differences in the kinetic sense, instead, it indicates that thermodynamic effects, namely differences in the stability of the acyl and the imidoyl radicals, control the overall course of the reactions.
Palladium-Catalyzed Intramolecular Selenocarbamoylation of Alkynes with Carbamoselenoates: Formation of α-Alkylidene-β-lactam Framework
Pd-catalyzed intramolecular selenocarbamoylation of alkynes leading to alpha-alkylidene-beta-lactams was developed. This reaction can be applied to thiocarbamoylation and to the synthesis of delta- and epsilon-lactams and a cyclobutanone.
Total Syntheses of the Marine Illudalanes Alcyopterosin I, L, M, N, and C
作者:Tania Welsch、Huu-Anh Tran、Bernhard Witulski
DOI:10.1021/ol102432q
日期:2010.12.17
The combination of a modular assembly of enantiopure triynes and a powerful rhodium-catalyzed [2 + 2 + 2] alkynecyclotrimerization reaction opens new and efficient entries to a set of alcyopterosins, including the first total synthesis of the alcyopterosins L, M, and C.