On the Behavior of α,β-Unsaturated Thioaldehydes and Thioketones in the Diels−Alder Reaction
作者:Guang Ming Li、Shuqiang Niu、Masahito Segi、Koichiro Tanaka、Tadashi Nakajima、Ralph A. Zingaro、Joseph H. Reibenspies、Michael B. Hall
DOI:10.1021/jo000740q
日期:2000.10.1
The calculations show that in the dimerization reaction of thioacrolein (I), the head-to-tail (S-C-S bonded) dimers are kinetically more stable by about 5 kcal/mol but slightly thermodynamically unstable by about 2 kcal/mol than the head-to-head (S-S bonded) dimers. The calculations on thiocinnamaldehyde (IV) indicate that the dimerization reactions of phenyl-substituted alpha,beta-unsaturated thioaldehydes
通过相应的羰基化合物与双(二甲基铝)硫化物的反应原位制备α,β-不饱和硫代醛和硫酮R1CH = CH-C(= S)R2。这些化合物会经历[4 + 2]自二聚反应,其中一个分子充当杂二烯成分,另一个分子充当亲二烯体,从而根据R1和R2提供不同类型的二聚体产物:1,2-二硫辛和1,3 -二硫辛(R1 = R2 = H),1,2-二硫辛(R1 = Ph,R2 = H,CH3)或二氢噻喃(R1 = R2 = Ph)。这些选择性差异是根据在DFT(密度泛函理论)水平上通过分子轨道(MO)计算得出的相对能量来解释的。计算表明,在硫代丙烯醛(I)的二聚反应中,头对尾(SCS键合)二聚体在动力学上比头对头(SS键合)二聚体稳定约5 kcal / mol,但热力学上不稳定约2 kcal / mol。关于硫代肉桂醛(IV)的计算表明,苯基取代的α,β-不饱和硫代醛和硫代酮的二聚反应几乎受热力学和动力学因素的控