Brønsted Acid Catalyzed Domino Aza‐Piancatelli Rearrangement/Michael Reaction: Construction of 1,4‐Benzodiazepin‐5‐ones in One Pot

Abstract

A para‐toluenesulfonic acid (pTSA) catalyzed domino aza‐Piancatelli rearrangement/Michael reaction was developed for the construction of 1,4‐benzodiazepin‐5‐ones in one pot. The method proceeds well in the presence of various furfurylcarbinols and o‐aminobenzamides to give products that contain medicinally relevant chemical entities.

Recent Advances on Piancatelli Reactions and Related Cascade Processes

“…By using this strategy, a variety of tricyclic cyclopentanone derivatives were constructed with the appropriate Lewis or Brønsted acid catalyst, such as La(OTf) 3 (Yu and Wang, 2012), 33 In(OTf) 3 , 34 and TsOH (Chandrasekhar, 2017). 35 Among the nucleophilic units used for this purpose, heteroatoms including NHTs, OH, SH, and CONH 2 successfully provided benzoxazines, tetrahydroquinoxalines, benzothiazines, and benzodiazepinones in high yields as single diastereomers (Scheme 9).…”

Solvent-Free Synthesis and Key Intermediate Isolation in Ni2Dy2 Catalyst Development in the Domino Ring-Opening Electrocyclization Reaction of Furfural and Amines

“…27 This organic transformation proceeds via a domino ring-opening/4π-electrocyclization pathway with only one equivalent of water generated as a side product. [28][29][30][31] This organic framework can be found in several natural products and thereafter several efficient methodologies that promote the synthesis of racemic, trans-4,5-diamino-2-cyclopentenones have been developed and recently reviewed. [32][33][34][35][36] The methodology reported by Nardi proceeds in water and is microwave assisted, , 35 whilst immobilized alternates have been reported.…”

Unprecedented Reactivity of γ‐Amino Cyclopentenone Enables Diversity‐Oriented Access to Functionalized Indoles and Indole‐Annulated Ring Structures

“…This rearrangement proceeds via a cascade process involving nucleophilic ringopening of furan ring with water to a pentadienyl cation and a subsequent 4p-electrocyclization, akin to Nazarov-type reactions. [3] Other variants namely, aza- [4,5] and carbo-Piancatelli [6] reactions have been subsequently developed using other nucleophilic partners. Transposed addition of nucleophile to furfuryl cation is the key to affect such rearrangement.…”

“…On the other hand, aza-Piancatelli reactions were successfully elaborated into domino processes, not by changing the reactants type, but using functionalized anilines or furylcarbinols, which led to complex molecular assemblies (Scheme 1 a). [5] Presence of a pendant latent reactive group on reactants that could be tolerated through entire rearrangement process and finally could elicit a secondary reaction, laid the foundation to these developments.…”