Studies in claisen rearrangements claisen rearrangement of bispropargyl ethers
About: This article is published in Tetrahedron Letters.The article was published on 1973-01-01. It has received 3 citations till now. The article focuses on the topics: Carroll rearrangement & Claisen rearrangement.
Citations
More filters
TL;DR: In this article, the authors focus on the advances in the chemistry of chrom-3-enes and their derivatives, focusing on the behavior of 2,2-dialkyl chromenes.
Abstract: Publisher Summary This chapter focuses on the advances in the chemistry of chrom-3-enes. No quantum mechanical calculation, or similar theoretical treatment seems to have been dedicated to chrom-3-ene or to its simple derivatives. Interatomic distances and angles of two bromo derivatives of natural chromenes have been obtained by X-ray analysis. The UV absorption, emission, fluorescence, and fluorescence excitation spectra of some 2,2-dialkylchromenes have been studied in connection with their photochromic behavior. Almost every class of natural phenolic compounds contains examples of substances with a 2,2-dialkylchromene ring, and the number of those that are discovered increases every year. It would be difficult to give an exhaustive list of these compounds. Their chemistry is discussed here only when it is related to some particular behavior of the benzopyran ring. Much progress has been made in the last, ten years in the synthesis of chrom-3-enes. Most of the activity has been stimulated by the discovery of new natural products and by the suggestions of possible biosynthetic pathways. In general, the reactions of chromenes are those expected from styrenes. Perhaps for this reason little attention has been paid to their chemical behaviour in recent years. Among chromenes, only the spiropyrans and their heterocyclic derivatives have found a wide practical application as photochromic substances. Chromenes with structure and activity similar to those of hashish constituents have been prepared. A number of chromenes, mostly with aryl substituents in positions 2,3 and 4 have been patented as biologically active substances.
14 citations
Patent•
01 Jun 1990TL;DR: In this paper, a solvent process for the conversion of aromatic propargyl ethers into chromenes is described, which can be catalyzed with copper or zinc salts, and the most preferred solvent is a dichlorobenzene.
Abstract: This invention relates to a solvent process for the conversion of aromatic propargyl ethers into chromenes The process can be catalyzed with copper or zinc salts The preferred salt is cuprous chloride The most preferred solvent is a dichlorobenzene The invention also relates to chromene products formed using the process and to the polymerization of that chromene product and its polymerized product, the latter product having substantially improved flexural modulus and flexural strength properties The polymerized product is also moisture insensitive
13 citations
TL;DR: Kalpattu Kuppuswamy Balsubramanian (popularly and affectionately addressed as KKB) was born on September 5th 1939, at Mylapore, Madras (now Chennai), Tamil Nadu, India, in a family gifted with tradition in the noble profession of teaching.
Abstract: Kalpattu Kuppuswamy Balsubramanian (popularly and affectionately addressed as KKB) was born on September 5th 1939, at Mylapore, Madras (now Chennai), Tamil Nadu, India, in a family gifted with tradition in the noble profession of teaching.[...]
2 citations
References
More filters
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
TL;DR: In this paper, a new synthetic method for various 4-substituted-3-chromenes was proposed, where phenyl propargyl ethers underwent intramolecular cyclization to give 4-chromene derivatives by heating with diethylaniline.
Abstract: This is a new synthetic method for various 4-substituted-3-chromenes : phenyl propargyl ethers underwent intramolecular cyclization to give 4-chromene derivatives by heating with diethylaniline. The reaction mechanism was clarified by the study of substituted phenyl propargyl ethers under the consideration of their electronic effects on the yields of resulting 3-chromene ; in general, the presence of +R group enhanced the cyclization, whereas -R group gave much lower yields of the corresponding chromenes. Therefore, this intramolecular cyclization is concluded to be an electrophilic reaction.
100 citations
TL;DR: In this paper, a base-catalysed Wessely-Moser rearrangement of simple phenols was proposed. But the results were limited to the case of ageratochromen and evodionol methyl ethers.
Abstract: α,α-Dimethylpropargyl ethers of simple phenols are readily prepared in high yields. Thermal rearrangement of them affords 2,2- dimethylchromens, also in high yields. These reactions are used to prepare the natural products, ageratochromen, evodionol methyl ether, lapachenole, seselin, luvangetin, and braylin. A base-catalysed Wessely-Moser rearrangement is reported.
69 citations
61 citations
54 citations