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.
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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.[...]
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15 citations
14 citations
01 Jan 1971
TL;DR: The transition state geometry of the aromatic Claisen and Cope rearrangements is discussed in this article, showing that a boat-like geometry is involved to an extent of 40 − 90%.
Abstract: Recent developments of some aromatic pericyclic reactions are reviewed.
The transition state geometry of the aromatic Claisen and Cope rearrangements is discussed. Whereas a chair-like geometry is favoured normally, the stereochemistry of the products resulting from the thermal rearrangement of methyl-substituted threo-2-(α-methylallyl)-cyclohexa-3,5-dien-l-ones indicates that a boat-like geometry is involved to an extent of 40 − 90%.
Bridged biphenyl and binaphthyl allyl and propargyl ethers, which possess a ground state conformation favourable for a [3s, 3s) -rearrangement are transformed thermally, even at temperatures between 25 − 130°, into dienones and their further rearrangement products.
A new 2-allyl phenol → coumaran rearrangement, as well as a one step synthesis of a twistadienone, is described.
Propargyl aryl and cycloheptatrienyl ethers yield, by multistep rearrangement processes, new cyclic compounds. For example, 2,6-dimethylphenyl ether on heating, followed by treatment with acid, is transformed into the 1,2,4-trimethyl-tropyliumion in good yield. Some photochemical reactions of tricyclic ketones, resulting from the thermal rearrangement of propargyl aryl ethers, are mentioned.
13 citations
TL;DR: In this paper, the rearrangement of 1,4-bis-aryloxybut-2-ynes to 4b,9b-dihydro-4b, 9b-dimethylbenzofuro (3,2-b) benzofuran is described.
12 citations
TL;DR: In this article, the thermal rearrangement of prop-2-ynyl kojate to the novel furo[3,2-b]pyrone in high yield is described.
Abstract: The thermal rearrangement of prop-2-ynyl kojate (2) to the novel furo[3,2-b]pyrone (6) in high yield is described.
8 citations