Gold-catalyzed [2+2+2+2]-annulation of 1,3,5-hexahydro-1,3,5-triazines with alkoxyallenes

Abstract

An unprecedented gold-catalyzed [2+2+2+2]-annulation of 1,3,5-hexahydro-1,3,5-triazines with alkoxyallenes has been developed, providing eight-membered heterocycles in good to excellent yields. Deuterium labeling and control experiments reveal the possible reaction mechanism for this annulation.

[4+2]‐Cycloaddition of para‐Quinone Methides with Hexahydro‐1,3,5‐Triazines: Access to 1,3‐Benzoxazine Derivatives

“…In addition to the utilization of 1,3,5‐triazines as Mannich reagents in aminomethylation protocols, they could also serve as efficient 1,4‐dipoles or 1,2‐dipoles in the construction of biologically important N‐containing heterocyclic ring structures through cycloaddition . Representative examples including the [3+2] cycloaddition, [2+1+2] cycloaddition, [2+2+2] cycloaddition, [3+2+2] cycloaddition, [4+3] cycloaddition, [2+2+2+2] cycloaddition, and [4+1]/[4+3] cycloaddition, were sequentially investigated as valuable cycloaddition reactions for the synthesis or modification of drug or drug‐like complex heterocyclic molecules. Compared with these well‐developed types of cycloaddition processes, [4+2]‐cycloaddition reactions with 1,3,5‐triazines acting as the 1,2‐dipoles have been relatively less investigated.…”

Recent Advances of 1,3,5-Triazinanes in Aminomethylation and Cycloaddition Reactions

“…Remarkably, the Sun group revealed that gold catalysis also enabled a novel [2+2+2+2]-annulation reaction between 1,3,5-triazinanes 2 and alkoxyallenes 57, providing eight-membered heterocycles 58 in good to excellent yields (Scheme 26a). 30 In their previous study, the gold-catalyzed reaction of allenamides with 1,3,5-triazinanes in a 1:1 ratio resulted in the formation of only six-membered heterocycles. 28 However, as shown in Scheme 26b, one equivalent of 2c and 57a yielded 58a and 58a′ in 43% and 56% yields, respectively.…”

Inverse‐Electron‐Demand [4+2]‐Cycloaddition of 1,3,5‐triazinanes: Facile Approaches to Tetrahydroquinazolines

“…[13] Subsequently, Feng [14] and Kang [15] reported the asymmetric Mannich reaction of 1,3,5-triazinanes, respectively. [23] In addition, Werz [21] and later also our group [24] reported the [3 + 2] cycloaddition of 1,3,5-triazinanes to access pyrrolidines, respectively. [23] In addition, Werz [21] and later also our group [24] reported the [3 + 2] cycloaddition of 1,3,5-triazinanes to access pyrrolidines, respectively.…”