S–Co(II) cascade catalysis: cyclocondensation of aromatic nitriles with alkamine

2-(Azolyl)anilines: methods of synthesis, cyclocondensations, and biological properties

“…It was shown, that tetrazole 35 was formed in almost quantitative yield (95%) by treatment of benzonitrile 34 with sodium azide in DMF in the presence of zinc sulfate nanospheres at 120°С with the reaction time up to 36 h (method B). Qi et al 10 Valgeirsson et al 13 The method for synthesis of 2-(4,5-dihydrooxazol-2-yl)-aniline (41) was described in the work of Ge et al 17 It was found that the optimal conditions are sulfur and Co(NO 3 ) 2 as the catalyst system90°C temperature with conventional or microwave (800 W) heating without solvent. It is noteworthy, that the solvent-free conditions were not only beneficial in reagent costs, but also more efficient than reaction in a solvent (Scheme 13).…”

“…In the cited paper the role of catalyst and mechanism of the reaction was discussed in detail. 17 Li 18 discussed tandem synthesis of 2-(4,5-dihydrothiazol-2-yl)aniline (42) and 2-(4,5-dihydrooxazol-2-yl)aniline (41). It was shown that 2-aminobenzonitrile (34) with 2-mercaptoethylammonia chloride or 2-aminoethanol with various copper catalysts and bases formed compounds 42 and 41, respectively (Scheme 14).…”

Microwave-Assisted Synthesis of Bioactive Six-Membered Heterocycles and Their Fused Analogues

“…Further post-modification has been showcased by the MW-assisted CuI catalyzed intramolecular amidation within 3,4-dihydro-3-oxo-2H-1,4-benzoxazines 276 affording an original heterocyclic scaffold 277 (Scheme 63). A two-component solvent-free procedure for the synthesis of 2-oxazines 265 under thermal and MW conditions has been described by Ge et al [259]. Thus, mono-and bisoxazines were selectively synthesized in good to excellent yields and with shortened reaction times (Scheme 60).…”

“…Therefore, the benzo[1,4]-oxazin-3-one scaffold can be pointed out as a very "privileged pharmacophore" [256][257][258]. A two-component solvent-free procedure for the synthesis of 2-oxazines 265 under thermal and MW conditions has been described by Ge et al [259]. Thus, mono-and bisoxazines were selectively synthesized in good to excellent yields and with shortened reaction times (Scheme 60).…”

Copper N-Heterocyclic Carbene Complexes As Active Catalysts for the Synthesis of 2-Substituted Oxazolines from Nitriles and Aminoalcohols

“…Recently, Ge and co-workers have used a catalytic amount of Co(NO 3 ) 2 to synthesize 2-subtituted oxazolines, 12 with elemental sulfur added as a nitrile activator. Moreover, Fu and co-workers reported that Zn(OTf) 2 in toluene at reflux is an active catalyst for the synthesis of chiral pyridine bis(oxazoline) ligands.…”