Substituent Effect on the Efficiency of Desulfurizative Rearrangement of Allylic Disulfides

Fluorinated Analog NMR s of Organosulfur Compounds from Garlic (Allium sativum): Synthesis, Chemistry and Anti-Angiogenesis and Antithrombotic Studies

We describe the synthesis, reactivity, and antithrombotic and anti-angiogenesis activity of difluoroallicin (S-(2-fluoroallyl) 2-fluoroprop-2-ene-1-sulfinothioate) and S-2-fluoro-2-propenyl-l-cysteine, both easily prepared from commercially available 3-chloro-2-fluoroprop-1-ene, as well as the synthesis of 1,2-bis(2-fluoroallyl)disulfane, 5-fluoro-3-(1-fluorovinyl)-3,4-dihydro-1,2-dithiin, trifluoroajoene ((E,Z)-1-(2-fluoro-3-((2-fluoroallyl)sulfinyl)prop-1-en-1-yl)-2-(2-fluoroallyl)disulfane), and a bis(2-fluoroallyl)polysulfane mixture. All tested organosulfur compounds demonstrated effective inhibition of either FGF or VEG-mediated angiogenesis (anti-angiogenesis activity) in the chick chorioallantoic membrane (CAM) or the mouse Matrigel^® models. No embryo mortality was observed. Difluoroallicin demonstrated greater inhibition (p < 0.01) versus organosulfur compounds tested. Difluoroallicin demonstrated dose-dependent inhibition of angiogenesis in the mouse Matrigel^® model, with maximal inhibition at 0.01 mg/implant. Allicin and difluoroallicin showed an effective antiplatelet effect in suppressing platelet aggregation compared to other organosulfur compounds tested. In platelet/fibrin clotting (anti-coagulant activity), difluoroallicin showed concentration-dependent inhibition of clot strength compared to allicin and the other organosulfur compounds tested.

NHC-catalyzed homoenolate reaction of enals and nitroalkenes: computational study of mechanism, chemoselectivity and stereoselectivity

A mechanistic study on the NHC-catalyzed homoenolate reaction of enals and nitroalkenes has been performed with the aid of DFT calculations.

Protecting group-free glycoligation by the desulfurative rearrangement of allylic disulfides as a means of assembly of oligosaccharide mimetics

2-(2-Pyridyldithio-3-butenyl) glycosides react with carbohydrate-based thiols in a two-step process involving sulfenyl transfer followed by desulfurative 2,3-allylic rearrangement, promoted by either triphenylphosphine or silver nitrate, to give novel saccharide mimetics. In an alternative embodiment of the same chemistry anomeric thiols are coupled with carbohydrates derivatized in the form of 2-(2-pyridyldithio-3-butenyl) ethers. This new method of glycoligation does not require protection of hydroxyl groups and is compatible with the presence of acetamides, azides, trichloroethoxycarbamates, and thioglycosides. Variations on the general theme enable the preparation of mimetics of reducing and nonreducing oligosaccharides as well as of nonglycosidically linked systems.

Silver-mediated allylic disulfide rearrangement for conjugation of thiols in protic media

Alkyl and aryl allyl disulfides are induced to undergo the desulfurative allylic rearrangement by silver nitrate in protic solvents at room temperature, thereby removing the necessity for the use of phosphines as thiophilic reagents. The silver-mediated reaction functions at ambient temperature in protic solvents and in the absence of protecting groups.

Synthesis of neoglycoconjugates by the desulfurative rearrangement of allylic disulfides

Two series of neoglycosyl donors are prepared on the basis of connection of an allylic disulfide motif to the anomeric center via a simple O-glycosyl linkage or N-glycosyl amide unit. Conjugation of both sets of donors to cysteine in peptides is demonstrated through classical disulfide exchange followed by the phosphine-mediated desulfurative allylic rearrangement resulting in neoglycopeptides characterized by a simple thioether spacer. The conjugation reaction functions in the absence of protecting groups on both the neoglycosyl donor and peptide in aqueous media at room temperature.