Chemodivergent photocatalytic access to 1-pyrrolines and 1-tetralones involving switchable C(sp3)-H functionalization
Shijing Tu1, Zhongyu Qi1, Weicai Li1
1Central Nervous System Drug Key Laboratory of Sichuan Province, Department of Medicinal Chemistry, School of Pharmacy, Southwest Medical University, Luzhou, China.
Abstract:
A chemodivergent photocatalytic approach to 1-pyrrolines and 1-tetralones from alkyl bromides and vinyl azides has been developed through chemoselectively controllable intermolecular [3 + 2] and [4 + 2] cyclization. This photoredox-neutral two-component protocol involves intermolecular radical addition and switchable distal C(sp3)-H functionalization enabled by iminyl radical-mediated 1,5-hydrogen atom transfer. Meanwhile, chemoselectivity between C(sp3)-N bond formation and C(sp3)-C(sp2) bond formation is precisely switched by photocatalysts (Ru(bpy)3(PF6)2 vs. fac-Ir(ppy)3) and additives (base vs. acid).
Related Concept Videos
Photochemical Electrocyclic Reactions: Stereochemistry
Selection Rules: Photochemical Activation
Cycloaddition Reactions: MO Requirements for Photochemical Activation
Thermal and Photochemical Electrocyclic Reactions: Overview
Cycloaddition Reactions: Overview
Cycloaddition Reactions: MO Requirements for Thermal Activation
Thermal Electrocyclic Reactions: Stereochemistry
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.

![Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F60786.jpg&w=3840&q=50)
