H-1-, C-13-, and N-15-NMR chemical shifts for selected glucosides and ribosides of aromatic cytokinins

The H-1 and C-13 NMR resonances of 16 purine glucosides were assigned by a combination of one- and two-dimensional NMR experiments, including gs-COSY, gs-HSQC, and gs-HMBC, in order to characterize the effect of substituent and the position of glucose unit on the NMR chemical shifts. In addition, N-15 NMR chemical shifts for selected derivatives were investigated by using H-1-N-15 chemical shift correlation techniques. To map the influence of sugar moiety on the directly bonded nitrogen atom, selected N-9-glucosides and their ribose analogs were compared. Characteristic long-range H-1-N-15 coupling constants, measured by using H-1-N-15 gradient-selected single-quantum multiple bond correlation (GSQMBC), are also reported and discussed. All compounds investigated here belong to cytokinins, an important group of plant hormones. Copyright (C) 2010 John Wiley & Sons, Ltd.