- Reactions of Cyclopropenes, VIII. - Transition Metal Catalyzed Cycloadditions of 3,3-Dimethoxycyclopropene
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Transition metal catalyzed cyclooligomerisations of 3,3-dimethyloxycyclopropene (1) yielding 2, 4 and 6 as well as cyclocodimerisations of 1 with electron deficient olefins leading to cis/trans-7 (with methyl acrylate) or trans-8 (with dialkyl fumarate or dialkyl maleate) can be performed under mild conditions. - In order to achieve cyclodimerisation yielding 2 phosphane-free palladium(0) catalysts are necessary, e.g. bis(dibenzylideneacetonePd(0) , whereas with phosphane-containing Pd(0) catalysts the cyclotrimer 4 is the main product besides little 2 and the cyclotetramer 6.On the other hand, phosphane-free Ni(0) compounds, such as bis(1,5-cyclooctadiene)nickel , are the best catalyst for the cyclocodimerisations. - The cyclodimer 2 is thermolabile and can be rearranged into chinone tetramethyl acetal (3) by heating to 110 deg C.
- Binger, Paul,Biedenbach, Bruno
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p. 601 - 606
(2007/10/02)
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