Research Progress of 1,3,5-Triazinanes in the Synthesis of Nitrogen-Containing Heterocycles

Abstract

1,3,5-Triazinanes are an important class of synthons, which could be regarded as the equivalent of formaldehyde imines in constructing various nitrogen-containing heterocyclic skeletons. In recent years, 1,3,5-triazinanes have attracted much attention in the construction of nitrogen-containing heterocyclic compounds. Based on this, the participation of 1,3,5-triazinanes as diatomic, triatomic and four-atom synthons in [2＋n], [3＋n], [4＋n] cycloaddition reactions to construct nitrogen-containing heterocyclic compounds is systematically summarized. Its applications in cycloaddition, heterocyclic chemistry and pharmaceutical chemistry are also summarized. Moreover, the development of 1,3,5-triazinanes in the construction of nitrogen-containing heterocyclic skeletons and their future applications are also prospected.

Copper-Catalyzed Cycloadditions of Diazo Compounds with Imidazolidines/Hexahydropyrimidines for the Syntheses of N-Heterocycles

“…Second, the types of 1,n-dipoles for the cycloaddition with diazo metal-carbenes are quite limited. Of special interest to the current study, Sun and co-workers discovered that 1,3,5-triazinanes could be used as 1,4-dipole precursors in the gold-catalyzed formal [4 + 1]/[4 + 3] cycloadditions with diazo compounds to produce five-/seven-membered N-heterocycles, in which the catalytically generated diazo gold-carbenes/gold-enolcarbenes reacted as 1,1-/1,3-dipolar adducts (Scheme a) . Also, a recent report showed that imidazolidines were potent 1,5-dipoles and participated well in the rhodium-catalyzed formal [5 + 1]/[5 + 3] cycloadditions with N-sulfonyl 1,2,3-triazoles, wherein the in situ generated α-imino rhodium-carbenes worked as 1,1-/1,3-dipolar species, to afford regiodivergent N-heterocycles, pyrazino-indolines and triazocines (Scheme b) …”

Recent Advances on High-Order Dipolar Annulations of Donor–Acceptor Cyclopropanes/Cyclobutanes

“…In recent years, 1,3,5-triazinanes 18 have attracted much attention and could act as diaza-four-atom synthons to participate in (4+n) cycloadditions for the rapid construction of various nitrogen-containing heterocycles. 19 In 2017, Werz and co-workers developed a (3+4) annulation of DACs with 1,3,5triazinanes 21, leading to 1,3-diazepane products 22 (Scheme 10).…”

“…Besides (hetero-)-1,3-dienes, several other four-atom synthons could also react with DACs via (3+4) annulations, including 1,3,5-triazinanes, 15 4-alkenyl indoles 16 and 4alkynyl indoles. 17 In recent years, 1,3,5-triazinanes 18 have attracted much attention and can act as diaza four-atom synthons in (4+n) cycloadditions for the rapid construction of various nitrogen-containing heterocycles. 19 In 2017, Werz and co-workers developed a (3+4) annulation of DACs with 1,3,5-triazinanes 21, leading to 1,3-diazepane products 22 (Scheme 10).…”

Visible-light-induced [1,3]-brook rearrangements of α-ketoacylsilanes and their subsequent trapping in a tandem annulation with 1,3,5-triazinanes and azomethine imines

“…1,3,5-Triazinanes are stable and readily available synthons, which have been extensively used as formal 1,n-dipoles in the rapid assembly of biologically important heterocycles. 9 Herein, we conceived that 1,3,5-triazinanes might be ideal candidates to react with α-ketoacylsilanes to achieve a novel and unprecedented tandem annulation sequence under mild reaction conditions. Additionally, the construction of a range of privileged scaffolds would represent key structural motifs in terms of unique applications in organic transformation and medicinal chemistry.…”