Metal-Free Synthesis of (E)-Monofluoroenamine from 1-Sulfonyl-1,2,3-triazole and Et₂O·BF₃ via Stereospecific Fluorination of α-Diazoimine

Abstract

A general, stereospecific, and straightforward method for the rapid preparation of functionalized (E)-monofluoroenamines is reported. Rather than transition metals (Rh, Ni, Pd, Cu, Ag, etc.), EtO·BF was employed to promote the formation of α-diazoimine through the Dimroth equilibrium of common 1-sulfonyl-1,2,3-triazole for the first time. An overall migration of fluoride from boron to the diazo-linked carbon of α-diazoimine was achieved. Derivations and late-stage modification of bioactive molecule were conducted. A plausible mechanism was also proposed.

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

“…In 2018, Li and co-workers described the first stereospecific transformation of N-sulfonyl-1,2,3-triazoles 7 into (E)-βensulfonylamido fluorides 8′ using Et 2 O•BF 3 as a Lewis acid (Figure 1C). 16 The authors determined the stereochemistry on the CC bond based on the 3 J F−H coupling constant. As stated in the article, the observed 3 J F−H of 25.4 Hz is a typical value for the cis isomer.…”

Stereoselective Synthesis of (Z)‐β‐Enamido Triflates and Fluorosulfonates from N‐Fluoroalkylated Triazoles

“…Considering the high stabilityo fc arbon-nitrogen bond of N-fluoroalkyl triazoles in comparison with the sulfur-nitrogen bond of N-sulfonyl triazoles [42] and good hydrolytic stability of 1,2,3-triazoles and their salts, [43][44][45][46] we assumed that the addition of as trong Brønsted acidw ould yield at riazolium salt that might lead to ring opening, nitrogen elimination, and ultimately afford an enamine (Scheme 1A).…”

Uncatalyzed Addition and Cyclization of T_SN₃to 1,1-Enediamines: An Effective Green Route to Highly Functionalized 1,2,3-Triazole Compounds

“…The 1,2,3-triazole skeleton usually contains that of synthesized drugs, for example, an anti-epileptic agent (rufinamide), anti-bacterial drug (tazobactum), heat shock protein 90 (Hsp90) inhibitor (SST0287CL1) [13], carbonic anhydrase inhibitor (compound A) [14], anti-influenza A agents (compound B) [15], et al [16]. At the same time, 1,2,3-triazole compounds are important building blocks for the synthesis of other N-containing heterocycles [17][18][19][20]. Therefore, there has been great interest in the synthesis of 1,2,3-triazole compounds in the fields of organic and pharmaceutical chemistry.…”