Studies in claisen rearrangement : Novel thermal transformation of α-aryloxymethylacrylic acids and their derivatives
TL;DR: In this paper, the structure of α-Aryloxymethylacrylic acids and their derivatives has been revised on the basis of degradation studies, extensive spectral data and isolation of intermediates.
About: This article is published in Tetrahedron.The article was published on 1985-01-01. It has received 9 citations till now. The article focuses on the topics: Claisen rearrangement & Ene reaction.
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TL;DR: The Baylis-Hillman reaction was first reported by Morita and Hillman as discussed by the authors, who reported the reaction of acetaldehyde with ethyl acrylate and acrylonitrile in the presence of catalytic amounts of 1,4-diazabicyclo[2.2] octane to give the α-hydroxyethylated products in good yields.
Abstract: In a patent application published in 1972, Baylis and Hillman reported the reaction of acetaldehyde with ethyl acrylate and acrylonitrile in the presence of catalytic amounts of 1,4-diazabicyclo[2.2.2]octane to give the α-hydroxyethylated products in good yields. No structure proof was given. The assignment eventually was shown to be correct, but since the initial disclosure was not followed by a journal publication, this remarkably simple, atom-efficient, and useful reaction was ignored for a number of years, and it has been only fairly recently that its potential has begun to be explored. The transformation is now commonly referred to as the Baylis–Hillman reaction. This is unfortunate because credit for its invention clearly belongs to Morita, who five years earlier, in patents and a brief paper reported the same reaction with the exception that tertiary phosphines were used as the catalysts; he also proposed the currently accepted mechanism. Baylis and Hillman made reference to Morita's work in their patent application. It is true that tertiary amines in general are cheaper, less toxic, and more readily removed than tertiary phosphines. However, the latter sometimes give higher yields in shorter reaction times, and there are a number of examples where they are the only useful catalysts.
The DABCO-catalyzed reaction is slow, and reaction times at room temperature of days or even weeks are common. Attempts to remedy this situation by use of other amine catalysts, change of reaction temperature, high pressure, or microwave irradiation have been partially successful. Activated olefins other than acrylonitrile and acrylic esters that have now been shown to undergo the reaction include α,β-unsaturated aldehydes and ketones, vinyl sulfoxides, vinyl sulfones, vinylsulfonates, and vinylphosphonates. β-Substituted activated olefins do not normally react. Among electrophiles other than aldehydes, unactivated ketones undergo the Morita–Baylis–Hillman reaction only under high pressure, but activation such as in α-halo ketones, α-keto esters, α-keto lactones, and nonenolizable α-diketones often produces very reactive substrates. Imines also can be employed, provided they carry a sufficiently electronegative group on nitrogen.
This chapter covers catalyzed α-hydroxyalkylations and α-aminoalkylations of activated olefins. Transition metal catalyzed reactions of this type, are also included even though they proceed by a different mechanism. Transformations that require stoichiometric amounts of reagents or more than one step are summarized in the section on Comparison With Other Methods but are not included in the Tabular Survey. The Morita–Baylis–Hillman reaction has been reviewed before.
Keywords:
catalysts;
hydroxyalklyation;
aminoalkylation;
activated olefin;
acrylates;
allenic esters;
acrylamides;
acrylonitrile;
acrolein;
unsaturated ketones;
vinyl sulfoxides;
vinyl sulfones;
vinylsulfonates;
vinylphosphonates;
substituted activated olefins;
electrophile;
intramolecular reactions;
side reactions;
aldehydes;
diketones;
keto esters;
keto lactones;
imines;
iminium salts;
Aldol and Michael reactions;
Morita-Baylis-Hillman reaction;
comparison of methods;
synthetic utility;
experimental conditions;
experimental procedures;
tabular survey
90 citations
Patent•
08 Dec 2009
TL;DR: The use of substituted heterocyclic compounds and pharmaceutical compositions containing the same that are capable of inhibiting or antagonizing a family of receptor tyrosine kinases, Tropomysosin Related Kinases (Trk), in particular the nerve growth factor (NGF) receptor, TrkA, is discussed in this paper.
Abstract: The present invention relates to novel synthetic substituted heterocyclic compounds and pharmaceutical compositions containing the same that are capable of inhibiting or antagonizing a family of receptor tyrosine kinases, Tropomysosin Related Kinases (Trk), in particular the nerve growth factor (NGF) receptor, TrkA. The invention further concerns the use of such compounds in the treatment and/or prevention of pain, cancer, restenosis, atherosclerosis, psoriasis, thrombosis, or a disease, disorder or injury relating to dysmyelination or demyelination or the disease or disorder associated with abnormal activities of NGF recptor TrkA.
64 citations
TL;DR: Ozonolysis of mono-substituted alkenes A-1 followed by reacting with a preheated mixture of CH2Br2-Et2NH affords α-substantituted acroleins A-2 in good yields.
40 citations
TL;DR: In this paper, the addition of various substituted phenols to allylic acetates obtained from Baylis-Hillman adducts has been studied in the presence of a Pd(0) catalyst and/or KF/alumina.
37 citations
TL;DR: Bronsted acids induced the intramolecular cyclisation of 3-aryloxypropanoic esters affording 3-methyl-4-chromanones, which have been transformed into the corresponding racemic benzyl β-oxoesters.
35 citations
References
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TL;DR: In this article, 2-Methylbenzo[b]furans and 2-methylbenzo [b]-thiophens were obtained from the corresponding chloroallyl phenyl ethers and phenyl sulphides, respectively.
Abstract: 2-Methylbenzo[b]furans and 2-methylbenzo[b]-thiophens were prepared in good yield from the corresponding chloroallyl phenyl ethers and chloroallyl phenyl sulphides, respectively.
6 citations
5 citations
4 citations
TL;DR: In this article, the synthesis of α-methylene- δ-valerolactones fused onto an unsaturated functionalized ring has been investigated and structure 5 is proposed for this compound.
3 citations