ABSTRACT
A new glycosylation method promoted by visible light with 3,5-dimethoxyphenyl glycoside as the donor was developed. This protocol delivers both O-glycosides and N-glycosides in moderate to excellent yields using a wide range of O-nucleophiles and nucleobases as the glycosyl acceptors.
ABSTRACT
An efficient protocol for the O-sialylation using thiosialoside donors under visible light photocatalysis was developed. Thiosialosides were activated under the irradiation with blue light in the presence of Ru(bpy)3(PF6)2 as photocatalyst, Umemoto's reagent as CF3 radical source and Cu(OTf)2 as an additive in acetonitrile/dichloromethane at -30 °C, and the subsequent reaction with glycosyl acceptors generally produced the desired sialosides in good to excellent yields with the satisfactory α-selectivity.
ABSTRACT
A glycosyl coupling reaction via photoinduced direct activation of thioglycosides and subsequent O-glycosylation in the absence of photosensitizer was developed for the first time. This reaction underwent a selectively homolytic cleavage of a C-S bond to generate a glycosyl radical, which was oxidized to an oxacarbenium ion by Cu(OTf)2, and a sequential O-glycosylation. A wide range of glycosides were synthesized in moderate to excellent yield using sugars, amino acids, or cholesterol as the acceptors.
Subject(s)
Glycosides/chemical synthesis , Thioglycosides/chemistry , Glycosides/chemistry , Glycosylation , Molecular Structure , Photochemical ProcessesABSTRACT
Unsymmetric acridines are synthesized via a one-pot amination/cyclization/aromatization reaction for the first time. With Pd(OAc)2-X-Phos as the catalyst, a series of unsymmetric acridines are obtained in moderate to excellent yields (up to 99% yield). Meanwhile, the diphenylamine intermediate could be isolated, which is evidence of the domino process.
Subject(s)
Acridines/chemical synthesis , Diphenylamine/chemistry , Palladium/chemistry , Acridines/chemistry , Amination , Catalysis , Cyclization , Molecular StructureABSTRACT
CuBr was found to be an efficient catalyst for the C-N cross coupling reaction of purine and diaryliodonium salts. 9-Arylpurines were synthesized in excellent yields with short reaction times (2.5 h). The method represents an alternative to the synthesis of 9-arylpurines via Cu(II) catalyzed C-N coupling reaction with arylboronic acids as arylating agents.
Subject(s)
Bromides/chemistry , Copper/chemistry , Hydrocarbons, Iodinated/chemistry , Purines/chemistry , Purines/chemical synthesis , Catalysis , Crystallography, X-Ray , Models, Molecular , Molecular Structure , Salts/chemistry , StereoisomerismABSTRACT
Purine is utilized as a new directing group for the Pd-catalyzed monoarylation of 6-arylpurines with simple aryl iodides via C-H bond activation in good yields, providing a complementary tool for the modification of 6-arylpurines (nucleosides). Most importantly, purine can be used as a building block for nucleoside derivatives, and the use of purine as a directing group helps avoid additional synthetic steps.