Reaction of 2-phenyltrimethinium salt 1 with thiourea and subsequent reaction with chloroacetic acid afforded 5-phenyl-2(1H)-pyrimidinone (3). Its silyl derivative 4 was condensed with 1-O-acetyl-2,3,5-tri-O-benzoyl-D-ribofuranose under catalysis with tin tetrachloride or trimethylsilyl trifluoromethanesulfonate to give protected nucleoside 5 together with 5',O6-cyclo-5-phenyl-1,3-bis- (β-D-ribofuranosyl)-6-hydroxy-5,6-dihydro-2(1H,3H)-pyrimidinone (7). The greatest amounts of 7 were formed with the latter catalyst. Nucleosidation of the silyl derivative 4 with protected methyl 2-deoxy-D-ribofuranoside 8 or 2-deoxy-D-ribofuranosyl chloride 9 afforded 1-(2-deoxy-3,5-di-O-p-toluoyl-β-D-ribofuranosyl)-5-phenyl-2(1H)-pyrimidinone (10) and its α-anomer 11. Reaction of 10 and 11 with methanolic ammonia gave free 2'-deoxynucleosides 12 and 13. Compound 13 was converted into 5'-O-tert-butyldiphenylsilyl-3'-O-mesyl derivative 14 which on heating with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and subsequent cleavage with tetrabutylammonium fluoride afforded 2',3'-dideoxy-2',3'-didehydronucleoside 15. Reaction of the silyl derivative 4 with 1,2-di-O-acetyl-3,5-di-O-benzoylxylofuranose (18), catalyzed with tin tetrachloride, furnished 1-(2-O-acetyl-3,5-di-O-benzoyl-β-D-xylofuranosyl)-2(1H)-pyrimidinone (19) which was deprotected to give the β-D-xylofuranosyl derivative 22. As a side product, the nucleosidation afforded the β-D-xylopyranosyl derivative 23. Deacetylation of compound 19 gave 1-(3,5-di-O-benzoyl-β-D-xylofuranosyl)-5-phenyl-2(1H)-pyrimidinone (24) which on reaction with thionyl chloride afforded 2'-chloro-2'-deoxynucleoside 25 and 2',O6-cyclonucleoside 26. Heating of compound 25 with DBU in dimethylformamide furnished the lyxo-epoxide 27 which on reaction with methanolic ammonia was converted into free 1-(2,3-anhydro-β-D-lyxofuranosyl)-5-phenyl-2(1H)-pyrimidinone (28). Reaction of 1,2-di-O-acetyl-5-O-benzoyl-3-O-methanesulfonyl-D-xylofuranose (30) with silyl derivative 4 gave the nucleoside 31 which by treatment with DBU was converted into an equilibrium mixture of 5'-benzoylated arabinofuranoside 33a and its 2',6-anhydro derivative 33b.
2-苯基三甲基铵盐1与硫脲反应,随后与氯乙酸反应,得到5-苯基-2(1H)-嘧啶酮(3)。其硅烷衍生物4在锡四氯化物或三甲基三氟甲磺酸硅烷酯的催化下与1- O-乙酰基-2,3,5-三- O-苯甲酰-D-核糖呋喃酮缩合,得到受保护的核苷5,以及5',O6-环-5-苯基-1,3-双(β-D-核糖呋喃基)-6-羟基-5,6-二氢-2(1H,3H)-嘧啶酮(7)。后一催化剂形成的7最多。硅烷衍生物4与受保护的甲基2-脱氧-D-核糖呋喃苷8或2-脱氧-D-核糖呋喃基氯化物9核苷化,得到1-(2-脱氧-3,5-二-O- p-甲苯基-β-D-核糖呋喃基)-5-苯基-2(1H)-嘧啶酮(10)及其α异构体11。10和11与甲醇氨反应,得到游离的2'-脱氧核苷12和13。化合物13转化为5'- O- tert-丁基二苯基硅烷基-3'- O-甲磺酰基衍生物14,经DBU加热和四丁基铵氟化物裂解,得到2',3'-二去氧-2',3'-二脱氢核苷15。硅烷衍生物4与1,2-二-O-乙酰-3,5-二-O-苯甲酰木糖呋喃酮(18)在锡四氯化物的催化下反应,得到1-(2-O-乙酰-3,5-二-O-苯甲酰-β-D-木糖呋喃基)-2(1H)-嘧啶酮(19),去保护后得到β-D-木糖呋喃基衍生物22。作为副产物,核苷化产生了β-D-木糖吡喃基衍生物23。化合物19的脱乙酰化反应得到1-(3,5-二-O-苯甲酰-β-D-木糖呋喃基)-5-苯基-2(1H)-嘧啶酮(24),与氯化硫酰反应得到2'-氯-2'-脱氧核苷25和2',O6-环核苷26。化合物25在二甲基甲酰胺中与DBU加热,得到lyxo-环氧化物27,与甲醇氨反应得到自由的1-(2,3-脱水-β-D-lyxofuranosyl)-5-苯基-2(1H)-嘧啶酮(28)。1,2-二-O-乙酰-5-O-苯甲酰-3-O-甲磺酰-D-木糖呋喃酮(30)与硅烷衍生物4反应,经DBU处理后转化为5'-苯甲酰化的阿拉伯糖呋喃核苷33a及其2',6-脱水衍生物33b的平衡混合物。