A proton nmr follow-up provided conclusive evidence for the involvement of two sequential Claisen rearrangements in the thermal rearrangement of 1,4-diaryloxy-2-butynes 1to 11a-methylpterocarpans 3. A detailed study of the rearrangement of 1,4-diaryloxy-2-butynes 1 in polyethyleneglycol-200 (PEG-200), indicated a definite possibility of selective synthesis of either benzofuron (3,2-b )benzofuran 4 or benzofuro(2,3-b)benzofuran 5 by varying the temperature of the reaction alone. © 1984.

K. Narayanan

Kalapattukuppuswamy Kuppuswamy B. Balasubramanian

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IIT Madras

On the claisen rearrangement of 1,4-diaryloxy-2-butynes

Tetrahedron

A systematic study of the behaviour of aryl γ-halopropargyl ethers under thermal condition was undertaken. Aryl γ-bromopropargyl ethers 2 underwent unique transformation in N,N-diethylanillne (215°C, 6 h) giving rise to a mixture of products 3,4and 5, whereas, under similar conditions aryl γ-chloropropargyl ethers ulbar|8, afforded 4-chlorochromenes, 9. A remarkable substituent and solvent effect has been observed in the thermolysis of these aryl γ-bromo and γ-chloropropargyl ethers, rendering this transformation as a method for the synthesis of a number of substit uted 4-bromochromenes 3, 4-chlorochromenes 9 and chroman-4-ones 7. In contrast, solution thermolysis of aryl γ-iodopropargyl ether 11 afforded aryl propargyl ether 1 as the major product. © 1989.

Thermal behaviour of aryl γ-haloprcpargyl ethers

Mastering French

Have You Had a Good Day? What Did You See?

The Journal of Organic Chemistry

Acid catalysis of the Claisen rearrangement. 2. Formation of the benzofurobenzopyran and benzofuro[3,2-b]benzofuran skeletons from 1,4-bis(aryloxy)-2-butynes

Synthesis

The Claisen Rearrangement in Organic Synthesis; 1967 to January 1977

Studies in claisen rearrangement—VI

Journal	Tetrahedron
ISSN	00404020
Open Access	No