Šagud Ivana, Antol Ivana, Marinić Željko, Šindler-Kulyk Marija
Department of Organic Chemistry, Faculty of Chemical Engineering and Technology, University of Zagreb , Marulićev trg 19, 10000 Zagreb, Croatia.
J Org Chem. 2015 Oct 2;80(19):9535-41. doi: 10.1021/acs.joc.5b01504. Epub 2015 Sep 30.
A new approach to benzo[f]quinoline derivatives has been found by an effective formal [4 + 2] photocycloaddition process from novel aryl-substituted o-vinylstyryl-2-oxazoles. All of the o-vinylstyryl-2-oxazoles were synthesized by a multicomponent Wittig reaction from the diphosphonium salt of α,α'-o-xylene dibromide, formaldehyde, and 5-tolyl-, 4-phenyl-5-methyl-, and 4,5-diphenyloxazole-2-carbaldehydes. TD-DFT calculations revealed that the intramolecular photocyclization in 2-(2-vinylstyryl)oxazoles to form benzo[f]quinoline derivatives proceeds on the S1 PES via a stepwise pathway, namely by 10π followed by 6π ring closure. On that path the existence of an S0/S1 conical intersection was indicated. The reactivity of the photocyclization steps depends on the substitution pattern at positions 4 and 5 of the oxazole ring, where the aryl group in position 5 deactivates the reaction.
通过一种有效的形式上的[4 + 2]光环化加成过程，从新型芳基取代的邻乙烯基苯乙烯基-2-恶唑中发现了一种合成苯并[f]喹啉衍生物的新方法。所有的邻乙烯基苯乙烯基-2-恶唑都是由α,α'-邻二甲苯二溴化二鏻盐、甲醛以及5-甲苯基-、4-苯基-5-甲基-和4,5-二苯基恶唑-2-甲醛通过多组分维蒂希反应合成的。含时密度泛函理论（TD-DFT）计算表明：2-(2-乙烯基苯乙烯基)恶唑分子内光环化形成苯并[f]喹啉衍生物是通过S1势能面上的逐步途径进行的，即先经10π环化，然后是6π环化。在该途径上表明存在S0/S1锥形交叉点。光环化步骤的反应活性取决于恶唑环4位和5位的取代模式，其中5位上的芳基会使反应失活。
