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In our recently developed interrupted Pummerer reaction mediated (IPRm) glycosylation with S-2-[(propan-2-yl)sulfinyl] benzyl (SPSB) glycosides as glycosyl donors, the anomeric leaving groups were recovered in the forms of thiosulfinate, disulfide and thiosulfonate. These products were presumed to be obtained by the hydrolysis and disproportionation of a cyclic thio-sulfonium intermediate. In this study, mass spectrometry and 1H NMR studies were carried out which confirmed that the cyclic thio-sulfonium intermediate exists. Further 18O isotopic labeling reactions revealed that the cyclic thio-sulfonium ion was hydrolyzed to thiosulfinate which further disproportionated to disulfide and thiosulfonate. This study clarifies the activation process of the SPSB glycosides involved glycosylation reactions. [ABSTRACT FROM AUTHOR]

Desulfurization is a versatile synthetic tool in organic synthesis, particularly in peptide chemistry, where it offers an effective conversion strategy for compounds that contain mercaptan groups. In this study, we present a metal-free desulfurization method for amino acids and peptides using a Togni-II reagent as a radical initiator. Our method showed excellent efficiency and extensive substrate tolerance, circumventing the formation of radical adducts caused by VA-044. The obtained results further expand the applicability of Togni-II reagent as a key promotor in radical-based reactions. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: The discovery of Kahne glycosylation forwards a big step in the carbohydrate chemistry. Despite an extensive series of studies, the precise mechanism of this powerful glycosylation is still not fully understood. To address these 30‐year puzzles, the far side of Kahne glycosylation is explored in this study. After a series of control and tracking experiments, a number of important intermediates including glycosyl oxo‐sulfonium ion and sulfenic anhydride (Crich's intermediate) are suggested to be responsible for the complex reaction pathway. It also reveals that in addition to the conventional ionic glycosylation pathway, a novel free radical pathway is very likely to contribute to the various side‐and co‐products. This study provides further understanding of Kahne glycosylation, and it also sheds light on how to improve the efficiency of sulfoxide‐based glycosylation reactions. [ABSTRACT FROM AUTHOR]

Main observation and conclusion: Based on the redox reactions of Togni‐II reagent and thiols, a thiol‐tuned selective functionalization of unactivated olefins was disclosed. In combination with aryl thiols, stoichiometric amount of Togni‐II reagent prompted a hydrotrifluoromethylation of alkenes, in which, aryl thiols played as reductant and hydrogen source; while by utilization of alkyl thiols, catalytic amount of Togni‐II reagent initiated thiol‐ene and thiol‐yne reactions. The reported applications are characterized by their operational simplicity and wide functional group tolerance. [ABSTRACT FROM AUTHOR]

Potassium (K) fixation and release in soil are important factors affecting K availability to plants and the utilization efficiency of K fertilizer. Three typical soils (red soil, yellow cinnamon soil, and alluvial soil) were collected from the middle and lower reaches of Yangtse River, China, to study the K-fixation and K-release characteristics of the normal and K-exhausted soil. Results showed that K fixation of added K in K-exhausted soils were significantly (P< 0.05) greater than that of the normal soils. There were significantly (P< 0.05) negative correlations among K-fixation capacity, concentration of soil-available K, and K+saturation. Irrespective of soil K exhaustion, K fixation of added K was in the order of red soil > yellow cinnamon soil > alluvial soil, but the cumulative amount of K released from the three soils during successive extractions with 1.0 mol L−1nitric acid (HNO3) was in the opposite order. The cumulative amounts of K released with 1.0 mol L−1ammonium acetate (NH4OAc) and 1.0 mol L−1HNO3extraction increased with the increasing numbers of extractions. The K-releasing power of soil by successive extraction decreased gradually and finally became almost constant. The release of K was lower in K-exhausted soil than in normal soil. Overall, the information obtained in this study will be helpful in formulating more precise K fertilizer recommendations for certain soils. [ABSTRACT FROM AUTHOR]