摘要:
The mixture of sec-butyllithium and potassium tert-butoxyde (LICKOR reagent) in THF at -95 degrees C, promotes smooth 1,4-eliminative process in 1,1-diethoxybut-2-ene (1) to afford conjugate (E)-1-ethoxybuta-1-3-diene (2). Moreover, when 2 equivalents of the mixed base are sued for 1 equivalent of the substrate, further metallation of the derivative 2 takes place affording the corresponding alpha-substituted derivatives 4a-e. Intermediates 4b-c and 4e can be converted by aqueous methanolic hydrochloric acid into the corresponding carbonyl compounds 5b-c and 5e. On the other hand, in mild acid (E)-3-tert-butyl-4-ethoxy-2,2-dimethylthepta-4,6-dien-3-ol (4d) cyclizes in a one-pot synthetic sequence to 2,2-di-tert-butyl-3-ethoxy-5-methyl-2,5-dihydrofuran (5d).