66086-24-6Relevant academic research and scientific papers
Alkynes and Cumulenes, XII. The Application of Di-tert-butyl Acetylenedicarboxylate in Diels-Alder Additions
Weber, Gisela,Menke, Klaus,Hopf, Henning
, p. 531 - 541 (2007/10/02)
Di-tert-butyl acetylenedicarboxylate (1) may be added in good yields to the model dienes 1,3-butadiene (6a), 2-methyl-1,3-butadiene (6b), 2,3-dimethyl-1,3-butadiene (6c), furan (10), and 1,3-cyclohexadiene (19) to afford the Diels-Alder adducts 7a-c, 12 (E = CO2C(CH3)3), and 20, respectively.Under certain conditions the reaction with 10 also laeds to the four 2:1-adducts 13-16 (E = CO2C(CH3)3).Whereas the esters 7a-c are converted in quantitative yields to the corresponding anhydrides 8a-c by warming in the presence of catalytic amounts of p-toluenesulfonic acid or by heating in substance, the decomposition of 12 and 20 stops at the stage of the monoesters 17 and 21, respectively.Competition experiments show that 1 is approximately three times less reactive towards 6c than dimethyl acetylenedicarboxylate (11).It is shown that 1 is a useful dienophile for the preparation of "mixed" paracyclophanes of type 28.
