Serafino Andrea, Chiminelli Maurizio, Balestri Davide, Marchiò Luciano, Bigi Franca, Maggi Rai-Mondo, Malacria Max, Maestri Giovanni
Department of Chemistry, Life Sciences and Environmental Sustainability, Università di Parma Parco Area Delle Scienze 17/A 43124 Parma Italy
IMEM-CNR Parco Area Delle Scienze 37/A 43124 Parma Italy.
Chem Sci. 2022 Jan 26;13(9):2632-2639. doi: 10.1039/d1sc06719b. eCollection 2022 Mar 2.
The visible-light-promoted activation of conjugated C-C double bonds is well developed, while that of cumulated systems is underexplored. We present the feasibility of this challenging approach. The localization of a triplet on an allenamide arm can be favored over that on a conjugated alkene. Allenamides with an arylacryloyl arm dimerize at room temperature in the presence of visible light and an iridium(iii) photocatalyst. Two orthogonal polycyclizations took place and their outcome is entirely dictated by the substitution of the alkene partner. Both cascades afford complex molecular architectures with high selectivity. Products form through the ordered rearrangement of twelve π electrons, providing a [3.2.0] bicyclic unit tethered to a fused tricycle, whose formation included an aryl C-H functionalization step, using disubstituted alkenes. The outcome was reverted with trisubstituted ones, which gave rise to taxane-like bridged tricycles that had two six-membered lactams flanking a cyclooctane ring, which was established through the creation of four alternate C-C bonds.
共轭碳 - 碳双键的可见光促进活化已得到充分发展，而累积体系的活化则研究不足。我们展示了这种具有挑战性的方法的可行性。三重态在烯丙酰胺臂上的定位可能比在共轭烯烃上更有利。带有芳基丙烯酰基臂的烯丙酰胺在可见光和铱（III）光催化剂存在下于室温下二聚。发生了两种正交的多环化反应，其结果完全由烯烃伙伴的取代决定。两个级联反应都以高选择性提供了复杂的分子结构。产物通过十二个π电子的有序重排形成，提供了一个连接到稠合三环的[3.2.0]双环单元，其形成包括使用二取代烯烃的芳基C - H官能化步骤。对于三取代烯烃，结果则相反，产生了紫杉烷类桥连三环，其具有两个位于环辛烷环两侧的六元内酰胺，这是通过形成四个交替的C - C键建立的。
