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Journal ArticleDOI

A Kinetic Study of the ortho-Claisen Rearrangement1

01 Jul 1958-Journal of the American Chemical Society (American Chemical Society)-Vol. 80, Iss: 13, pp 3277-3285
About: This article is published in Journal of the American Chemical Society.The article was published on 1958-07-01. It has received 113 citations till now. The article focuses on the topics: Specific kinetic energy.
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Journal ArticleDOI
02 Nov 2012-Science
TL;DR: It is reported that Ullmann C–N coupling can be photoinduced by using a stoichiometric or a catalytic amount of copper, which enables the reaction to proceed under unusually mild conditions (room temperature or even –40°C).
Abstract: Carbon–nitrogen (C–N) bond-forming reactions of amines with aryl halides to generate arylamines (anilines), mediated by a stoichiometric copper reagent at elevated temperature (>180°C), were first described by Ullmann in 1903. In the intervening century, this and related C–N bond-forming processes have emerged as powerful tools for organic synthesis. Here, we report that Ullmann C–N coupling can be photoinduced by using a stoichiometric or a catalytic amount of copper, which enables the reaction to proceed under unusually mild conditions (room temperature or even –40°C). An array of data are consistent with a single-electron transfer mechanism, representing the most substantial experimental support to date for the viability of this pathway for Ullmann C–N couplings.

382 citations

Journal ArticleDOI
TL;DR: This paper showed that the known thermal cyclisation of aryl propargyl ethers to chromenes involves a preliminary [3, 3]-sigmatropic rearrangement.
Abstract: 2, 6-Dimethylphenyl propargyl ether (10) and its derivatives 12–15 rearrange thermally to 1, 5-dimethyl-6-methylene-tricyclo [3.2.1.02,7]oct-3-en-8-one (9) and related compounds 16–19. The ethers undergo first an aromatic [3, 3]-sigmatropic rearrangement to ortho-allenyldienones 11, which then undergo ring closure to the tricyclic products by an electrocyclic reaction. Only in the case of the γ-methylpropargyl ether 13, the ortho-dienone 11 is further rearranged in low yield to the para-butynylphenol 20, but the tricyclic ketone 17 is again the main product. New data show that the known thermal cyclisation of aryl propargyl ethers to chromenes (e. g. 4 8) involves a preliminary [3, 3]-sigmatropic rearrangement.

136 citations

Journal ArticleDOI
TL;DR: It is shown that the Claisen rearrangement drives phenolic C-prenylation in at least one case, suggesting that this route should be reconsidered as a mechanism for the biosynthesis of prenylated phenolic compounds.
Abstract: The enzymatic basis of ribosomal peptide natural product prenylation has not been reported. Here, we characterize a prenyltransferase, LynF, from the TruF enzyme family. LynF is the first characterized representative of the TruF protein family, which is responsible for both reverse- and forward-O-prenylation of tyrosine, serine, and threonine in cyclic peptides known as cyanobactins. We show that LynF reverse O-prenylates tyrosine in macrocyclic peptides. Based upon these results, we propose that the TruF family prenylates mature cyclic peptides, from which the leader sequence and other enzyme recognition elements have been excised. This differs from the common model of ribosomal peptide biosynthesis, in which a leader sequence is required to direct post-translational modifications. In addition, we find that reverse O-prenylated tyrosine derivatives undergo a facile Claisen rearrangement at ‘physiological’ temperature in aqueous buffers, leading to forward C-prenylated products. Although the Claisen rearr...

107 citations

Book ChapterDOI
01 Jan 1991
TL;DR: In this paper, a survey of variants of the Claisen rearrangement that are of general use in stereoselective organic synthesis is presented, highlighting the influence of steric and electronic parameters on transition state geometries.
Abstract: This article surveys variants of the Claisen rearrangement that are of general use in stereoselective organic synthesis. Recent results concerning the influence of steric and electronic parameters on transition state geometries are highlighted. The impact of the Claisen methodology in modern synthetic strategy and its application for the preparation of highly functionalized derivatives is exemplified.

100 citations

Journal ArticleDOI
TL;DR: Structural information on enzymes from two species, and on an antibody that catalyzes the same reaction, has shed new light on chorismate mutase's catalytic mechanism.

100 citations