120262-50-2Relevant academic research and scientific papers
Cycloaddition Reactions of 2-Cyclopropylidene-1,3-diones with Electron-Rich Alkynes
Vilsmaier, Elmar,Baumheier, Ruprecht
, p. 1285 - 1290 (2007/10/02)
Cyclopropylidenedimedone 3, an unstable and highly reactive intermediate, is trapped in a Hetero Diels-Alder reaction by the addition of ynamines 7a-c, f, ynether 7d, or phenylacetylene (7e).Heterolysis of the resulting cycloadducts 8a-d, f leads to carboxylic acid derivatives 9a-d, f.The latter may be regarded as the result of a twofold nucleophilic substitution at a cyclopropane system according to their synthesis by the sequence 17-> 5-> 8-> 9.An opening of the cyclopropane ring takes place during hydrolysis of cycloadduct 8e producing 11.Analogously, 2-cyclopropylidene-1,3-diones 13A-13C can be generated by aminocyclopropylation of CH acids 18A-18C and subsequent deamination induced by an acylation reaction.Trapping of 13A - 13C by ethoxyacetylene (7d) or ethyl vinyl ether (4) provides the analogous cycloadducts 14A, B and 15C. - Key Words: 2-Cyclopropylidene-1,3-diones / Hetero Diels-Alder reaction / Cyclopropane derivatives
