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A novel method for Fmoc/ tBu solution-phase peptide synthesis and the development of a new benzyl-type group-assisted purification (GAP) protecting group is reported. This GAP protecting group is utilized in place of a polymer support, facilitating C→N Fmoc peptide synthesis without chromatography or recrystallization. The GAP group can be added and removed in high yield, and was used to synthesize over 1 gram of the immunostimulant, thymopentin, in high overall yield (83 %) and purity (99 %). [ABSTRACT FROM AUTHOR]

A copper-free intramolecular azide–alkyne cycloaddition reaction of 4-hydroxymethyl-β-lactam with sodium azide has been described. The present approach involves the incorporation of an alkyne moiety through O-alkynylation of 3-hydroxy β-lactam with various propargylic halides. The generality of the method has been demonstrated by treating the corresponding tosylates or mesylates of the hydroxymethyl functionality of a variety of β-lactam-tethered terminal and internal alkynes with sodium azide in a one-pot three-step reaction to furnish novel oxazepane-β-lactam fused triazole scaffolds of diverse interest in good yield. A facile metal-free intramolecular [3 + 2] cycloaddition reaction on a stereo-defined prebuilt β-lactam template for the synthesis of tricyclic oxazepane triazole β-lactam scaffolds has been achieved. The resulting unique tricyclic skeleton is presumably difficult to achieve by other existing methods. This synthetic protocol is circumvents the dominance of the copper-catalyzed click reaction. [ABSTRACT FROM AUTHOR]

Various O and S -glycosyl esters and their corresponding acids are synthesized through a reaction of bromo sugar and benzyl glycolate in the presence of indium trichloride and indium tribromide as promoter. We discovered unprecedented catalytic effects of indium tribromide in glycosylation and hydrogenolysis in a one-pot operation. The sugar acid is a potential chiral auxiliary for the synthesis of biologically active compounds of diverse interests. [ABSTRACT FROM AUTHOR]

New silver-catalyzed tunable dimerization and trimerization reactions of β-alkynyl ketones have been established, enabling multiple C−C bond-forming events to selectively access skeletally diverse spiroisochromenes with generally good yields. The silver-enabled bicycloaddition of β-alkynyl ketones with water offered hydroxylated spiroisochromenes. Without water, spiroisochromenes with a methylene moiety were obtained through catalytic 6- endo-dig oxo-cyclization/[4+2] cycloaddition cascades by using pyridine as additive whereas employment of 1,1′-binaphthyl-2,2′-diyl hydrogen phosphate (BiNPO4H) as a Brønsted acid catalyst rendered the unprecedented dispiro trimerization products through double C( sp3)-H functionalization. [ABSTRACT FROM AUTHOR]

Various O and S-glycosyl esters and their corresponding acids are synthesized through a reaction of bromo sugar and benzyl glycolate in the presence of indium trichloride and indium tribromide as promoter. [ABSTRACT FROM AUTHOR]