[5-(Adenin-9-yl)-5-deoxy-L-pentofuranosyl]phosphonates - A Novel Type of Nucleotide Analogs Related to HPMPA. II. Synthesis of L-ribo and L-xylo Configurated Derivatives by Recyclization of Diethyl (5-RS)-[1,2-O-Isopropylidene-5-O-methanesulfonyl-D-pentofuranos-5-C-yl]phosphonates under Acidic Conditions
[5-(Adenin-9-yl)-5-deoxy-L-pentofuranosyl]phosphonates - A Novel Type of Nucleotide Analogs Related to HPMPA. II. Synthesis of L-ribo and L-xylo Configurated Derivatives by Recyclization of Diethyl (5-RS)-[1,2-O-Isopropylidene-5-O-methanesulfonyl-D-pentofuranos-5-C-yl]phosphonates under Acidic Conditions