Related Experiment Video
Updated: Aug 31, 2026

Preparation of N-(2-alkoxyvinyl)sulfonamides from N-tosyl-1,2,3-triazoles and Subsequent Conversion to Substituted Phthalans and Phenethylamines
Published on: January 3, 2018
Rh(III)-Catalyzed Multicomponent Formal [4 + 2+1]/[4 + 1] Annulation for the Synthesis of
Qin Luo1, Meng-Zhen Wei1, Yi-Ting Wang1
1Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, School of Chemical Science and Technology, Yunnan University, Kunming, 650091, P. R. China.
Abstract:
A Rh(III)-catalyzed three-component cascade cyclization has been developed for the efficient synthesis of highly functionalized benzo[d]pyrazolo[1,5-a]azepin-4-ones (BPAPOs) from a sulfoxonium ylide, a vinyl diazo ester, and excess vinylene carbonate. The reaction proceeds through a formal [4 + 2+1]/[4 + 1] cyclization cascade, rapidly constructing the tricyclic BPAPO framework and forming five new chemical bonds in a one-pot process. Notably, the two stereocenters in the target molecules can be controlled through temperature-dependent diastereoselectivity: Temperature-controlled diastereoselectivity enables the selective formation of diastereomer 4 at 100 °C and diastereomer 5 at 70 °C, both with high dr values. Their relative configurations were confirmed by single-crystal X-ray diffraction. The method features broad substrate scope and good functional-group tolerance, providing efficient access to diverse tricyclic scaffolds for biological and medicinal chemistry.
Related Concept Videos
Diazonium Group Substitution with Halogens and Cyanide: Sandmeyer and Schiemann Reactions
Aryldiazonium Salts to Azo Dyes: Diazo Coupling
Nucleophilic Aromatic Substitution of Aryldiazonium Salts: Aromatic SN1
In the Sandmeyer reaction, for example, the diazonio group is replaced by a chloro, bromo, or cyano...
Diazonium Group Substitution: –OH and –H
Cyclohexenones via Michael Addition and Aldol Condensation: The Robinson Annulation
Nucleophilic Aromatic Substitution: Elimination–Addition

![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)