Department of Chemistry and Biochemistry, University of California-Los Angeles , 607 Charles E. Young Drive, Los Angeles, California 90095-1569, United States.
J Am Chem Soc. 2014 Feb 12;136(6):2397-403. doi: 10.1021/ja410220w. Epub 2014 Feb 4.
The intramolecular Diels-Alder reactions of cycloalkenones and terminal dienes occur with high endo stereoselectivity, both thermally and under Lewis-acidic conditions. Through computations, we show that steric repulsion and tether conformation govern the selectivity of the reaction, and incorporation of either BF3 or α-halogenation increases the rate of cycloaddition. With a longer tether, isomerization from a terminal diene to the more stable internal diene results in a more facile cycloaddition.
环烯酮和末端二烯的分子内 Diels-Alder 反应在热和路易斯酸性条件下都具有很高的内选择性。通过计算，我们表明空间位阻和连接体构象控制着反应的选择性，并且 BF3 的引入或α-卤化作用都提高了环加成的速率。对于较长的连接体，从末端二烯到更稳定的内二烯的异构化导致更易进行的环加成。
