4-amino-3-(2,3,5-tri-O-benzyl-β-d-ribofuranosyl)-5-pyrazolecarbonitrile. Synthesis and conversion into a sugar-blocked 5,7-disubstituted formycin analog
作者:Andre Rosowsky、Mitali Ghoshal、Vishnu C. Solan
DOI:10.1016/0008-6215(88)84056-4
日期:1988.5
intermediate to protected C-nucleoside analogs related to formycin A, was synthesized via a new route wherein 2,3,5-tri-O-benzyl-1-O-p-nitrophenyl)-D-ribofuranose was converted to 2,5-anhydro-3,4,6-tri-O-benzyl-D-allonic acid, and further transformed into 4-(tert-butyloxycarbonyl)-5-ethoxycarbonyl-3-(2,3,5-tri-O-benzyl-beta-D- ribofuranosyl)pyrazole. After amidation and dehydration to form the 4-(tert-
标题化合物是与甲霉素A相关的受保护C-核苷类似物的潜在中间体,它是通过新的途径合成的,其中将2,3,5-三-O-苄基-1-Op-硝基苯基)-D-呋喃核糖转化为2,5-脱水-3,4,6-三-O-苄基-D-丙二酸,并进一步转化为4-(叔丁氧羰基)-5-乙氧羰基-3-(2,3,5-三- O-苄基-β-D-呋喃核糖基)吡唑。在酰胺化和脱水以形成4-(叔丁氧基羰基)-5-吡唑甲腈之后,酸解然后是Curtius型序列,得到了4-氨基-5-吡唑-腈的核苷。在桑德梅尔型反应中用亚硝酸和氯化铜处理后者,得到重氮腈而不是氯腈。尝试将氨基腈或重氮腈转化为5,7-二氨基-3-(2,3,5-三-O-苄基-β-D-呋喃呋喃糖基)吡唑并[4,通过与胍或N,N-二甲基胍缩合的3-d]嘧啶(5-氨基甲霉素A)不成功。氨基腈与二硫化碳在吡啶中的缩合提供了以3-(2,3,5-三-O-苄基-β-D-呋喃呋喃糖基)吡唑并[4,3-d]嘧啶-