Kapil Upadhyaya
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Research Subjects
Kapil Upadhyaya has a total of 3 co-authors. Here are the top co-authors by number of shared publications:
- David Crich
University of Georgia
2 shared publications Yagya P. Subedi
Department of Pharmaceutical and Biomedical Sciences University of Georgia 250 West Green Street Athens GA 30602 USA
1 shared publication- Yagya Prasad Subedi
Department of Chemistry and Biochemistry, Utah State University, 0300 Old Main Hill, Logan, UT 84322-0300, USA
1 shared publication
Latest Publications
- 21 October 2021
- Published by Wiley in Angewandte Chemie International Edition
- Vol. 60 (48) , 25397-25403
Direct Experimental Characterization of a Bridged Bicyclic Glycosyl Dioxacarbenium Ion by 1H and 13C NMR Spectroscopy: Importance of Conformation on Participation by Distal Esters
Low‐temperature NMR studies with a 4‐C‐methyl‐4‐O‐benzoyl galactopyranosyl donor enable the observation and characterization of a bridged bicyclic dioxacarbenium ion arising from participation by a distal ester. Variable‐temperature NMR studies reveal this bridged ion to decompose at temperatures above ≈−30 °C. In the absence of the methyl group, the formation of a bicyclic ion is not observed. It is concluded that participation by typical secondary distal esters in glycosylation reactions is disfavored in the ground state conformation of the ester from which it is stereoelectronically impossible. Methylation converts the secondary ester to a conformationally more labile tertiary ester, removes this barrier, and renders participation more favorable. Nevertheless, the minor changes in selectivity in model glycosylation reactions on going from the secondary to the tertiary esters at both low and room temperature argue against distal group participation being a major stereodirecting factor even for the tertiary system.
- 21 October 2021
- Published by Wiley in Angewandte Chemie International Edition
- Vol. 60 (48) , 25397-25403
Direct Experimental Characterization of a Bridged Bicyclic Glycosyl Dioxacarbenium Ion by 1H and 13C NMR Spectroscopy: Importance of Conformation on Participation by Distal Esters
Low‐temperature NMR studies with a 4‐C‐methyl‐4‐O‐benzoyl galactopyranosyl donor enable the observation and characterization of a bridged bicyclic dioxacarbenium ion arising from participation by a distal ester. Variable‐temperature NMR studies reveal this bridged ion to decompose at temperatures above ≈−30 °C. In the absence of the methyl group, the formation of a bicyclic ion is not observed. It is concluded that participation by typical secondary distal esters in glycosylation reactions is disfavored in the ground state conformation of the ester from which it is stereoelectronically impossible. Methylation converts the secondary ester to a conformationally more labile tertiary ester, removes this barrier, and renders participation more favorable. Nevertheless, the minor changes in selectivity in model glycosylation reactions on going from the secondary to the tertiary esters at both low and room temperature argue against distal group participation being a major stereodirecting factor even for the tertiary system.
- 20 September 2021
- Published by Wiley in Angewandte Chemie
- Vol. 133 (48) , 25601-25607
Direct Experimental Characterization of a Bridged Bicyclic Glycosyl Dioxacarbenium Ion by 1H and 13C NMR Spectroscopy: Importance of Conformation on Participation by Distal Esters
Low‐temperature NMR studies with a 4‐C‐methyl‐4‐O‐benzoyl galactopyranosyl donor enable the observation and characterization of a bridged bicyclic dioxacarbenium ion arising from participation by a distal ester. Variable‐temperature NMR studies reveal this bridged ion to decompose at temperatures above ≈−30 °C. In the absence of the methyl group, the formation of a bicyclic ion is not observed. It is concluded that participation by typical secondary distal esters in glycosylation reactions is disfavored in the ground state conformation of the ester from which it is stereoelectronically impossible. Methylation converts the secondary ester to a conformationally more labile tertiary ester, removes this barrier, and renders participation more favorable. Nevertheless, the minor changes in selectivity in model glycosylation reactions on going from the secondary to the tertiary esters at both low and room temperature argue against distal group participation being a major stereodirecting factor even for the tertiary system.
- 20 September 2021
- Published by Wiley in Angewandte Chemie
- Vol. 133 (48) , 25601-25607
Direct Experimental Characterization of a Bridged Bicyclic Glycosyl Dioxacarbenium Ion by 1H and 13C NMR Spectroscopy: Importance of Conformation on Participation by Distal Esters
Low‐temperature NMR studies with a 4‐C‐methyl‐4‐O‐benzoyl galactopyranosyl donor enable the observation and characterization of a bridged bicyclic dioxacarbenium ion arising from participation by a distal ester. Variable‐temperature NMR studies reveal this bridged ion to decompose at temperatures above ≈−30 °C. In the absence of the methyl group, the formation of a bicyclic ion is not observed. It is concluded that participation by typical secondary distal esters in glycosylation reactions is disfavored in the ground state conformation of the ester from which it is stereoelectronically impossible. Methylation converts the secondary ester to a conformationally more labile tertiary ester, removes this barrier, and renders participation more favorable. Nevertheless, the minor changes in selectivity in model glycosylation reactions on going from the secondary to the tertiary esters at both low and room temperature argue against distal group participation being a major stereodirecting factor even for the tertiary system.