ABEN, RENE, W. M.;SCHEEREN, H. W., TETRAHEDRON LETT., 1983, 24, N 42, 4613-4616
作者:ABEN, RENE, W. M.、SCHEEREN, H. W.
DOI:——
日期:——
High pressure promoted (2+2) cycloadditions of ketene acetals with carbonyl compounds
作者:René W.M. Aben、Hans W. Scheeren
DOI:10.1016/s0040-4039(00)85970-5
日期:1983.1
Cycloadditions of ketene acetals (R1R2C=C(OR)2) with carbonylcompounds (R3COR4) are strongly promoted by increase or pressure. At 12 kbar oxetanes are even obtained from very polar ketene acetals (R1,R2=H,H or H,Cl) and - in the presence of a Lewis acid - with unactivated ketones (R3 and R4 = alkyl). The reaction proceeds via a cisoid dipolar transition state; when relevant mainly trans-substituted
通过增加或加压,可大大促进乙烯酮缩醛(R 1 R 2 C = C(OR)2)与羰基化合物(R 3 COR 4)的环加成反应。在12kbar下,甚至从极极性的乙烯酮缩醛(R 1,R 2= H,H或H,Cl)和在路易斯酸存在下由未活化的酮(R 3和R 4=烷基)获得氧杂环丁烷。该反应通过一个cisoid偶极过渡态进行。当相关时,主要形成反式取代的氧杂环丁烷。