Preparation of spiro[imidazolidine-4,3′-indolin]-2′-imines via copper(i)-catalyzed formal [2 + 2 + 1] cycloaddition of 3-diazoindolin-2-imines and triazines

Abstract

We report a facile and efficient synthesis of spiro[imidazolidine-4,3′-indolin]-2′-imines via a copper(i)-catalyzed cascade reaction of 3-diazoindolin-2-imines with 1,3,5-triazines.

A Three‐Component Reaction to Construct β‐Aminonitroso‐α‐Diazocarbonyl Compounds under Metal‐Free Conditions

“…In 2016, a gold‐catalyzed formal [4+1] cycloaddition of diazo esters with 1,3,5‐triazines to afford imidazolidines has been reported by Sun (Scheme 1b) [13] . Furthermore, Wang and co‐workers realized a copper(I)‐catalyzed cascade reaction of 3‐diazoindolin‐2‐imines with 1,3,5‐triazines (Scheme 1c) [14] . In addition, Sun's group have developed a metal‐free [2+1+2]‐cycloaddition reaction between tosylhydrazones and 1,3,5‐triazines to give imidazolidines (Scheme 1d) [15] .…”

“…[13] Furthermore, Wang and co-workers realized a copper(I)-catalyzed cascade reaction of 3diazoindolin-2-imines with 1,3,5-triazines (Scheme 1c). [14] In addition, Sun's group have developed a metal-free [2 + 1 + 2]-cycloaddition reaction between tosylhydrazones and 1,3,5-triazines to give imidazolidines (Scheme 1d). [15] However, the diazo group is lost in the above excellent examples.…”

Rhodium(II)‐Catalyzed [4+2] Annulation of Ester‐Tethered 1‐Sulfonyl‐1,2,3‐Triazoles and Hexahydro‐1,3,5‐Triazines

“…In 2019, Bao [11b] reported a novel reaction of 1‐sulfonyl‐1,2,3‐triazoles and hexahydro‐1,3,5‐triazines to synthesize octahydro‐1 H ‐purine derivatives (Scheme 1a). Shortly afterwards, an [4+1] annulation of a special 1‐sulfonyl‐1,2,3‐triazoles (most existed as 3‐diazoindolin‐2‐imines form in solid states) and hexahydro‐1,3,5‐triazines was reported by Lu and Wang [10i] (Scheme 1b). Our group reported an reaction of ester‐tethered 1‐sulfonyl‐1,2,3‐triazole with azirine to synthesize 1,2,3,4‐tetrahydropyrimidine in 2019 [12c] .…”

Synthesis of 3,4-Dihydro-2H-1,3-thiazines from α-Enolic Dithioesters and 1,3,5-Triazinanes via a Formal (3 + 3) Annulation Reaction

“…On the other hand, 1,3,5-triazinanes as a useful class of nitrogen-containing building blocks were widely used in organic synthesis recently (Scheme ). − For example, they could be adopted as two-atom synthons to undergo aminomethylation, hydroaminomethylation, and 1,5-(aryl)­aminomethylation reactions . In addition, they could undergo various annulation reactions with different reaction partners under transition-metal or Lewis-acid catalyzed conditions, − for example, [2 + n ], [3 + n ], and [2 + 2 + n ]/[4 + n ], in which different quantities of atoms from 1,3,5-triazinanes were incorporated into the products.…”

“… − For example, they could be adopted as two-atom synthons to undergo aminomethylation, hydroaminomethylation, and 1,5-(aryl)­aminomethylation reactions . In addition, they could undergo various annulation reactions with different reaction partners under transition-metal or Lewis-acid catalyzed conditions, − for example, [2 + n ], [3 + n ], and [2 + 2 + n ]/[4 + n ], in which different quantities of atoms from 1,3,5-triazinanes were incorporated into the products. Among them, for the type of three atoms (C–N–C) of 1,3,5-triazinane introduced to target molecule via sequential reactions, there was only one document disclosed by Sun recently .…”