Metal-free synthesis of imidazole by BF₃·Et₂O promoted denitrogenative transannulation of N-sulfonyl-1,2,3-triazole

Abstract

BF·EtO promoted metal-free denitrogenative transannulation of N-sulfonyl-1,2,3-triazole was reported. Rather than transition metals, BF·EtO was employed for the first time to promote the formation of α-diazoimines from N-sulfonyl-1,2,3-triazoles in nitriles, leading to the synthesis of various imidazoles. The protocol tolerates a broad range of functional groups and could also be applied to the late-stage modification of bioactive molecules, demonstrating the potential of this protocol in organic synthesis. A plausible mechanism was proposed.

Stereoselective Synthesis of (Z)-β-Enamido Fluorides from N-Fluoroalkyl- and N-Sulfonyl-1,2,3-triazoles

“…The formation of the same (E)-β-ensulfonylamido fluorides 8′ has been observed by the same group in the synthesis of imidazoles by Et 2 O•BF 3 -mediated transformation of Nsulfonyl-1,2,3-triazoles and nitriles. 21 On the basis of our previous findings of acid-mediated transformations of 1,2,3-triazoles and 3 J F−H coupling constants, which point to a trans rather than a cis 2A). The reaction afforded 13% of the product that was subjected to NMR studies.…”

Synthesis of Heterocycles through Denitrogenative Cyclization of Triazoles and Benzotriazoles

“…In 2018, Li and co-workers described aB F 3 •Et 2 O-promoted denitrogenative annulation reaction of N-sulfonyl-1,2,3-triazoles in nitriles,p roviding easy access to the synthesis of imidazoles 136 (Scheme 24). [42] This reactiont olerates ab road range of groups at variouss ubstitution sites of 1,2,3-triazoles 135 and nitriles. The proposed mechanism features the formation of the a-diazoimines intermediate…”

Rh‐Catalyzed Formal [3+2] Cyclization for the Synthesis of 5‐Aryl‐2‐(quinolin‐2‐yl)oxazoles and Its Applications in Metal Ions Probes

“…Therefore, the development of simple, efficient, and environmentally benign strategies for the formation of 2-(quinolin-2yl)oxazoles is quite appealing. Scheme 1 Synthetic strategies for 2-(quinolin-2-yl)oxazoles 2,triazoles have recently emerged as structural motifs that are studied for synthesizing a variety of biologically active heterocycles, [6] including pyrrole, [7] tetrahydropyridines, [8] imidazoles, [9] pyrroloindoline, [10] and others. [11] In these transformations, the highly reactive rhodium azavinyl carbenes (Rh-AVC), derived from Rh(II)-catalyzed denitrogenation of N-sulfonyl-1,2,3triazoles has been successfully employed as a [1C], [2C], or aza-[3C]-synthon in various [3+n] cycloaddition reactions.…”