1,3‐Dioxolium‐, 1,3‐dithiolium‐ und 1,3‐diselenolium‐ionen ‐ aromatische strukturen oder durch heteroatome stabilisierte carbeniumionen?

Timm, U.; Plücken, Udo; Petersen, H.; Meier, Herbert

doi:10.1002/jhet.5570160702

Cited by 21 publications

(1 citation statement)

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“…[571] In solution, however, the yields of selenoketene-derived 1,3-diselenols 809 are moderate (R 1 ϭ CO 2 Et, R 2 ϭ H, 18%; R 1 ϭ CO 2 Et, R 2 ϭ Me, 12%) [572] to poor [R 1 ,R 2 ϭ (CH 2 ) 4 , 9%]. [573] 1,4-Diselenines 811, together with alkynes 810, prevail. [574] Obviously, the tendency to undergo Wolff rearrangement decreases in the order α-diazo ketones Ͼ 1,2,3-thiadiazoles Ͼ 1,2,3-selenadiazoles.…”

Section: -Thiadiazoles and Related Substratesmentioning

confidence: 99%

100 Years of the Wolff Rearrangement

2002

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The conversion of α‐diazo ketones into ketenes, and products derived therefrom, was discovered by Wolff in 1902. Major applications of the Wolff rearrangement, such as the Arndt−Eistert reaction (homologation of carboxylic acids) and the ring contraction of cyclic ketones, have been with us for some while. Nevertheless, substantial progress has been made recently. The reaction mechanism has been explored by means of matrix isolation, time‐resolved spectroscopy, and computation. Full retention of configuration of the migrating group has been established by using enantioselective chromatography. The Arndt−Eistert reaction has witnessed a renaissance in the field of natural products, in particular β‐amino acids and β‐peptides. Ring‐contracting Wolff rearrangements and ketene cycloadditions have been applied in syntheses of increasingly complex, biologically active target molecules. These accomplishments, as well as unsolved problems, are addressed in the present review. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)

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Section: -Thiadiazoles and Related Substratesmentioning

confidence: 99%