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Preparation of 2-vinylcyclobutanones and their conversion to cyclopentenones

✍ Scribed by David A. Jackson; Max Rey; André S. Dreiding

Book ID
104226249
Publisher
Elsevier Science
Year
1983
Tongue
French
Weight
211 KB
Volume
24
Category
Article
ISSN
0040-4039

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✦ Synopsis

Methyl-and ethyl-vinylketene 2 were added to several simple olefins 1 to afford alkylated 2-vinylcyclobutanones 4, which in turn rearranged to cyclopentenones 5 (via dienones g,l) or l (via 1,2-acyl migration) under acid catalysis. Evidence is presented for a cyclopropyl-carbinyl intermediate 8. Following our interest' (cf. also2) in the reactions of vinylketenes, we have found that Our method to obtain 5, 5 and 1 uses the same building blocks (unsaturated acid derivatives and olefins) as the Friedel-Crafts approach to make linear dienones 12 and cyclopentenones. 13 Aside from affording vinylcyclobutanones 2 as potentially valuable intermediates, our method has the advantages of a) preventing contact between a strong acid and the starting olefin, thus avoiding double bond migration, and b) permitting in some cases an altogether milder acid catalysis, which could suppress decomposition.

📜 SIMILAR VOLUMES

2-Vinylcyclobutanones by Cycloaddition o
2-Vinylcyclobutanones by Cycloaddition of Vinylketenes to Simple Olefins
✍ David A. Jackson; Max Rey; André S. Dreiding 📂 Article 📅 1983 🏛 John Wiley and Sons 🌐 German ⚖ 719 KB

## Abstract Selected [2+2]‐cycloadditions of three alkylvinylketenes **2** to one mono‐ and seven dialkyl‐olefins **3** yielded eleven 2‐alkyl‐2‐vinylcyclobutanones **4** __(Tables 1__ and __2).__ Three methods were compared, all involving __in situ__ generation of the ketenes **2** by HCl‐eliminat

Conversion of 2-alkylcyclopentanones int
Conversion of 2-alkylcyclopentanones into 2-alkyl-2-cyclopentenones with hydrated ferric chloride and cupric chloride
✍ G. Cardinale; J. A. M. Laan; S. W. Russell; J. P. Ward 📂 Article 📅 2010 🏛 Elsevier Science 🌐 English ⚖ 429 KB

## Abstract Hydrated ferric chloride, FeCl~3~·6 H~2~O, in a polar, hydroxylic solvent converted 2‐alkylcyclopentanones directly into 2‐alkyl‐2‐cyclopentenones on heating in the presence of air. Yields of isolated products were about 40 %. The scope of the reaction is discussed. With cupric chloride