(CDC)–Rhodium-Catalyzed Hydroallylation of Vinylarenes and 1,3-Dienes with AllylTrifluoroborates
作者:Justin S. Marcum、Tia N. Cervarich、Rajith S. Manan、Courtney C. Roberts、Simon J. Meek
DOI:10.1021/acscatal.9b01579
日期:2019.7.5
generated as a result of transmetalation followed by Rh–(allyl) complex equilibration, consequently disproving outer-sphere addition of the allyl nucleophile to Rh(III)–(η3-allyl). (4) Stereochemical analysis of a cyclohexadiene allyl addition product supports a syn Rh(III)–hydride addition. (5) A Hammett plot shows a negative slope. Finally, utility is highlighted by a iodocyclization and cross metathesis
报道了乙烯基芳烃和1,3-二烯的催化位点选择性氢化烯化。易于获得的双齿碳二碳烯-铑配合物促进了转化,涉及到商业上可获得的烯丙基三氟硼酸酯和一种醇。该反应适用于乙烯基芳烃和芳基或烷基取代的1,3-二烯(30个例子)。烯丙基加成产物的产率为40-78%,位点选择性高达> 98:2。反应结果与通过酸质子化Rh(I)生成的Rh(III)-氢化物的中间体一致。给出了反应的许多关键机理细节:(1)氘争夺进入产物并且起始的烯烃表明可逆的Rh(III)–H迁移插入。(2)观察到较大的一次动力学同位素效应。(3)用取代的三氟硼酸烯丙酯(例如,3部位异构体的K)混合物作为转移金属化的结果,随后RH-(烯丙基)配合物平衡中产生,因此反驳外球加入烯丙基亲核试剂的Rh(III的) - (η 3 -烯丙基)。(4)环己二烯丙基烯丙基加成产物的立体化学分析支持顺式Rh(III)-氢化物加成。(5)哈米特图显示负斜率。最后,碘化和交叉易位突出了实用性。