Thiol Mediated Free Radical Cyclization of Alkenyl and Alkynyl Isocyanides
摘要:
Thiol-mediated free radical cyclizations of but-3-enyl and but-3-ynyl isocyanides of types 6-8 give new access to 3,5-disubstituted 2-(alkyl- and 2-(arylthio)pyrrolines 11, 12, and 18. When 2-mercaptoethanol is used with the same isocyanides the reaction results in pyroglutamates 16, 17, or 19. These cyclizations involve the formation of a new carbon-carbon bond through intramolecular addition of a carbon-centered thioimidoyl radical to a carbon-carbon multiple bond. Although cyclic products are usually obtained in high yields, in a few cases a competing radical degradation process leading to isothiocyanates was observed. Isocyanide 8a carrying an allyl(phenyl) sulfide moiety isomerizes to 2-(phenylthio)pyrroline 24 in a series of sequential steps.
Intramolecular Imidoylative Heck Reaction: Synthesis of Cyclic Ketoimines from Functionalized Isocyanide
作者:Jian Wang、Shi Tang、Qiang Zhu
DOI:10.1021/acs.orglett.6b01174
日期:2016.7.1
Efficient access to five- to seven-membered cyclic ketoimines, through palladium-catalyzed intramolecular imidoylative Heckreaction of alkene-containing isocyanides, has been developed. Consecutive isocyanide and alkene insertion into aryl or alkyl Pd(II) intermediates takes place in this process. No byproduct derived from monoinsertion or reversed sequence is detected.
A new straightforward entry into unsaturated nine-membered lactams of potential use as external reverse turn inducers was developed. It is based on an Ugi multicomponent reaction using two unsaturated substrates, followed by highly stereoselective ring-closingmetathesis (RCM). The synthesis of a nine-membered secondary lactam by RCM is reported for the first time.
approach for the synthesis of indane-based α-amino acid derivatives is reported. In this regard, the synthesis of five-membered exocyclic and five-membered inner-outer ring diene building blocks (7 and 15) containing α-amino acid moieties is described. Diene 15 is prepared by an enyne metathesis reaction as a key step. In this paper, a full account of our work regarding the Diels-Alderreaction of these dienes
Microwave-assisted synthesis of γ-thiolactams from ethyl isocyanoacetate
作者:Massimiliano Lamberto
DOI:10.1515/hc-2018-0005
日期:2018.6.27
Abstract γ-Thiolactams were synthesized in good yields from ethyl isocyanoacetate through a sequential alkylation/isothiocyanation/radical cyclization under microwave irradiation.
Synthesis of a diene building block via enyne metathesis reaction and its usage in the preparation of constrained alpha-amino acid derivatives is described. (C) 1998 Elsevier Science Ltd. All rights reserved.