Described herein is the expansion of the picoloyl protecting-group assisted H-bond mediated aglycone delivery (HAD) method recently introduced by our laboratory. At first it was noticed that high α-stereoselectivity is only obtained with S-ethyl glycosyl donors and only in the presence of dimethyl(methylthio)sulfonium trifluoromethanesulfonate (DMTST), in high dilution, and low temperature. Combining the mechanistic studies of the HAD reaction and bromine-promoted glycosylations allowed a very effective method to be devised that allows for highly stereoselective α-glycosidation of practically all common leaving groups (S-phenyl, S-tolyl, S/O-imidates) at regular concentrations and ambient temperature.
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http://dx.doi.org/10.1002/chem.201406589 | DOI Listing |
Curr Med Sci
October 2024
Key Laboratory of Novel Targets and Drug Study for Neural Repair of Zhejiang Province, School of Medicine, Hangzhou City University, Hangzhou, 310015, China.
Alzheimer's disease (AD) is one of the most common forms of neurodegenerative dementia. The etiology of AD is multifactorial, and its complex pathophysiology involves tau and amyloid-β deposition, increased oxidative stress, neuroinflammation, metabolic disorders, and massive neuronal loss. Due to its complex pathology, no effective cure for AD has been found to date.
View Article and Find Full Text PDFDrug Res (Stuttg)
November 2024
Department of Pharmacy, Integral University, Dasauli, Kursi road, Lucknow (U.P.)-India.
Bioflavonoids, are a diverse group of phytonutrients that are widely distributed in fruits, vegetables, grains, teas, and certain medicinal herbs. They are characterized by their antioxidant properties and play essential roles in plant biology, such as providing color to fruits and flowers, protecting plants from environmental stresses. Daidzein, a bioflavonoid classified under natural products, is sourced from plants like soybeans and legumes.
View Article and Find Full Text PDFChemistry
August 2024
Department of Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, 223-8522, Japan.
Mannosylerythritol lipids (MELs) are a class of amphipathic molecules bearing a hydrophilic 4-O-β-D-mannopyranosyl-D-erythritol skeleton. Here, we designed and synthesized four kinds of MEL analogues R-MEL-A ([2R,3S]-erythritol type), S-mannosylthreitol lipid (MTL)-A ([2S,3S]-threitol type), R-MTL-A ([2R,3R]-threitol type), and α-S-MEL-A ([2S,3R]-erythritol type) using our previously reported boron-mediated aglycon delivery (BMAD) method and a neighboring group assisted glycosylation method. The selective cytotoxicity of the target compounds against cancer cells was evaluated, with R-MTL-A showing the highest selective cytotoxicity against human skin squamous carcinoma HSC-5 cells.
View Article and Find Full Text PDFMolecules
April 2024
Department of Biotechnology, College of Life Sciences, Ritsumeikan University, Kusatsu 525-8577, Japan.
Rare sugars are known for their ability to suppress postprandial blood glucose levels. Therefore, oligosaccharides and disaccharides derived from rare sugars could potentially serve as functional sweeteners. A disaccharide [α-d-allopyranosyl-(1→2)-β-d-psicofuranoside] mimicking sucrose was synthesized from rare monosaccharides D-allose and D-psicose.
View Article and Find Full Text PDFJ Oleo Sci
April 2024
Department of Applied Chemistry, Faculty of Science and Technology, Keio University.
Mannosylerythritol lipid (MEL) has attracted much attention as an environmentally benign and biocompatible material in many research fields due to its significant biochemical and physiological properties. However, heterogeneity always exists in MEL obtained from microbial products with respect to the chain length of the fatty acids. In this context, the total synthesis of the 20 members of MEL was effectively and stereoselectively achieved using our boron-mediated aglycon delivery (BMAD) method.
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