Synthesis of [ 15 N 4 ] purine labeled cytokinin glycosides derived from zeatins and topolins with 9‐β‐ d , 7‐β‐ d ‐glucopyranosyl, or 9‐β‐ d ‐ribofuranosyl group

Synthesis of [ 15 N 4 ] purine labeled cytokinine glycosides derived from zeatins and topolins containing a 9‐β‐ d , 7‐β‐ d ‐glucopyranosyl, or 9‐β‐ d ‐ribofuranosyl group is described. These N 6 ‐substituted adenine derivatives are intended as internal analytic standards for phytohormone analysis. All labeled compounds were prepared from 6‐chloro[ 15 N 4 ]purine ( 1 ). The equilibrium reaction of 1 with acetobromo‐α‐ d ‐glucose gave isomeric 7‐β‐ d ( 3 ) and 9‐β‐ d ( 4 ) chloro glucosyl precursors, which were treated with the corresponding amines to get desired labeled cytokinin 7‐β‐ d ( 6 ) and 9‐β‐ d ( 5 ) glucopyranosides. Cytokinins containing 9‐β‐ d ‐ribofuranosyl group ( 8 ) were obtained by direct enzymatic transglycosylation reaction of cytokinins ( 7 ) prepared from 6‐chloro[ 15 N 4 ] purine ( 1 ).