1: (3AS,4S,6R,6AR)-6-(6-chloro-purin-9-yl)-2,2-dimethyl-tetrahydro-furo[3,4-d][1,3]dioxole-4-carboxylic acid With thionyl chloride in acetonitrile T=30°C; 4 h; 2: methylamine With N-ethyl-N,N-diisopropylamine in tetrahydrofuran; acetonitrile T=7°C; 13 h;