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Unexpected products from the reaction of 2,2,4,4-tetramethylcyclobutane-1,3-dione with the Makosza reagent


Mloston, Grzegorz; Romanski, Jaroslaw; Linden, Anthony; Heimgartner, Heinz (1999). Unexpected products from the reaction of 2,2,4,4-tetramethylcyclobutane-1,3-dione with the Makosza reagent. Helvetica Chimica Acta, 82:1302-1310.

Abstract

Reaction of 2,2,4,4-tetramethylcyclobutane-1,3-dione (2) under phase-transfer-catalysis (PTC) conditions (CHCl3/aqueous NaOH) yielded a complex mixture of unexpected products (Scheme 2). From the organic phase, three ring-enlarged products 7-9 with a cyclopentane-1,3-dione (cf. 7 and 9) or a cyclopentenone skeleton (cf. 8) were isolated in low yield. After acidification of the aqueous phase, the oily residue was treated with CH2N2 , and methyl 3-oxopentanoate 12 and dimethyl 2-hydroxybutanedioate 13 were obtained in almost equal amounts. The structures of 8 and 9 were established by X-ray crystal-structure analysis (Fig.). Mechanisms for the formation of the products, initiated by nucleophilic attack of trichloromethanide ion and opening of the cyclobutane ring, are proposed in Schemes 3 and 4.

Abstract

Reaction of 2,2,4,4-tetramethylcyclobutane-1,3-dione (2) under phase-transfer-catalysis (PTC) conditions (CHCl3/aqueous NaOH) yielded a complex mixture of unexpected products (Scheme 2). From the organic phase, three ring-enlarged products 7-9 with a cyclopentane-1,3-dione (cf. 7 and 9) or a cyclopentenone skeleton (cf. 8) were isolated in low yield. After acidification of the aqueous phase, the oily residue was treated with CH2N2 , and methyl 3-oxopentanoate 12 and dimethyl 2-hydroxybutanedioate 13 were obtained in almost equal amounts. The structures of 8 and 9 were established by X-ray crystal-structure analysis (Fig.). Mechanisms for the formation of the products, initiated by nucleophilic attack of trichloromethanide ion and opening of the cyclobutane ring, are proposed in Schemes 3 and 4.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Department of Chemistry
Dewey Decimal Classification:540 Chemistry
Language:English
Date:1999
Deposited On:05 Nov 2013 16:39
Last Modified:07 Dec 2017 23:24
Publisher:Wiley-Blackwell
ISSN:0018-019X
Funders:Polish State Committee for Scientific Research, Swiss National Science Foundation, F. Hoffmann-La Roche AG, Basel, Dr. Helmut Legerelotz Stiftung, Universität Zürich
Publisher DOI:https://doi.org/10.1002/(SICI)1522-2675(19990804)82:8<1302::AID-HLCA1302>3.0.CO;2-A

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