Heterocyclic β-keto sulfide derivatives of carvacrol: Synthesis and copper (II) ion reducing capacity

Sixteen β-keto sulfide derivatives of carvacrol (4–19) incorporating phenyl or N, O and S heterocyclic moieties were synthesized in three steps. The relationships between heterocyclic structure and cupric, Cu(II), ion reducing antioxidant capacity (CUPRAC) were examined. Nine of the compounds (8–9 and 13–19) showed better CUPRAC activity than trolox at neutral pH, with trolox equivalent antioxidant capacity (TEAC) coefficients ranging between 1.20 and 1.75. Two derivatives (11–12) showed comparable reducing capacity to trolox, with TEAC values of 0.95 for 11 and 1.02 for 12. Compounds 8–9 and 11–19 were more effective at reducing the Cu (II) ion than ascorbic acid and the parent compound, carvacrol. The most effective antioxidants were those containing an oxadiazole, thiadiazole or triazole moiety. In particular, the methyl thiadiazole derivative (15) had the highest Cu(II) ion reducing capacity, with a TEAC coefficient of 1.73

Antioxidant and tyrosinase docking studies of heterocyclic sulfide derivatives containing a thymol moiety

Fourteen heterocyclic sulfide derivatives (4–17) containing a thymol moiety and oxadiazole, thiadiazole, triazole, oxazole, thiazole, imidazole, pyridine or purine heterocycles were synthesized in three steps. The cupric, Cu(II), ion reducing antioxidant capacity of the compounds was examined, and molecular docking studies were performed to determine whether the sulfur, thymol or heterocyclic moieties interact with the Cu ions in tyrosinase, a type-3 copper enzyme. Using the CUPRAC assay, eight compounds (5–8, 10, 15–17) showed equal or better Cu (II) reducing capacity than trolox at neutral pH, with trolox equivalent antioxidant capacity (TEAC) coefficients ranging between 1.00 and 1.48. The compounds containing a thiadiazole moiety were most effective, with the methyl thiadiazole derivative (8) having the highest Cu(II) reducing capacity. Molecular docking studies of the sulfide derivatives with tyrosinase revealed that there were no direct interactions between the sulfur atom and the active site copper ions. However, the compounds displayed two different binding interactions with the histidine-Cu catalytic center. For compounds 4–13, the thymol portion was embedded in the active site cavity, while for compounds 14–17 the heterocyclic portion of the molecule approached the cavity

[3 + 2] Cycloadditions of Tertiary Amine N-Oxides and Silyl Imines as an Innovative Route to 1,2-Diamines

We have developed a one-pot synthetic method for producing 1,2-diamines from easily prepared and commercially available precursors through a formal umpolung process. Our method utilizes an efficient [3 + 2] cycloaddition as the key step in forming substituted 1,2-diamines in moderate to high yields. These resulting compounds can undergo subsequent transformations, demonstrating their utility as synthetic building blocks for more complex scaffolds. Finally, we propose a reasonable mechanism for this transformation using density functional theory modeling, justifying the experimental observations