P-Prolyl-nucleoside-P-methyl-phosphonamidites, P-chiral building blocks for nucleoside methylphosphonate synthesis were prepared by two different methods. First starting from dichloromethylphosphine 1 prochiral bis-proline-methylphosphines 3a-e were obtained. Their reaction with tritylthymidine in presence of an acid like tetrazole or better 2, 6-di-tert.- butyl-4-methyl-pyridinium-tetrafluoroborate furnished the amidites 5a-e. The absolute ...
