18793-23-2Relevant academic research and scientific papers
Synthesis of 3-Oxo-8-oxabicyclooct-6-ene-2-carbonitriles from γ-Bromo-β-oxonitriles and Furan via Cycloaddition of 1-Cyanoallylium-2-olates
Foehlisch, Baldur,Herter, Rolf,Wolf, Elisabeth,Stezowski, John J.,Eckle, Emil
, p. 355 - 380 (2007/10/02)
Some γ-bromo-β-oxonitriles 3 react with furan in the presence of silver oxide to form stereoselectively the title compounds 7.Satisfying yields are obtained only with those bromides 3, whose γ-carbon is tertiary or which are monoalkylated both at the α- and γ-carbon atoms.The results are explained by a cycloaddition of 1-cyanoallylium-2-olate intermediates (14) to the 1,3-diene system of the furan.With cyclic γ-bromo-β-oxonitriles (6) two types of cycloadducts were observed: 3-bromo-3-methyl-2-oxocyclohexanecarbonitrile (6b) and 3-bromo-2-oxocyclododecanecarbonitrile (6d) form the tricyclic cycloadduts 10b and d, analogs of the bicyclic adducts 7.With 3-bromo-2-oxocyclohexanecarbonitrile (6a) and 3-bromo-5-tert-butyl-2-oxocyclohexanecarbonitrile (6e), however, the carbonyl oxygen is connected with an α-carbon of the furan to give the tricyclic cycloadducts 12Aa and Ae.The structure endo-2,endo-4-dimethyl-3-oxo-8-oxabicyclooct-6-ene-exo-2-carbonitrile (7eα) was determined by X-ray analysis.
