Zinc-Catalyzed Cycloisomerizations. Synthesis of Substituted Furans and Furopyrimidine Nucleosides
作者:Adam Sniady、Audrey Durham、Marco S. Morreale、Andrzej Marcinek、Slawomir Szafert、Tadeusz Lis、Krystyna R. Brzezinska、Takanori Iwasaki、Takashi Ohshima、Kazushi Mashima、Roman Dembinski
DOI:10.1021/jo8007995
日期:2008.8.1
dichloromethane at room temperature gave 2,5-di- and 2,3,5-trisubstituted furans in high yields (85−97%). DSC studies confirmed that a solely thermal process does not take place. A relevant catalytic process, employing μ-oxo-tetranuclear zinc cluster Zn4(OCOCF3)6O, yielded bicyclic furopyrimidine nucleosides, when starting from acetyl-protected 5-alkynyl-2′-deoxyuridines (85−86%). Furopyrimidine was
在二氯甲烷中催化量的氯化锌醚化物(10 mol%)的存在下,1,4-和1,2,4-主要是芳基取代的but-3-yn-1-one的5- Endo - dig环异构化室温下以高收率(85-97%)得到2,5-二-和2,3,5-三取代的呋喃。DSC研究证实,不会发生完全的热过程。使用μ-氧代-四核锌簇Zn 4(OCOCF 3)6的相关催化过程当从乙酰基保护的5-炔基-2'-脱氧尿苷(85-86%)开始时,O产生双环呋喃嘧啶核苷。使呋喃嘧啶脱保护或同时转化为吡咯并嘧啶核苷。1-苯基-4-(4-甲基苯基)丁炔酮与2-(4-甲基苯基)-5-苯基呋喃反应的时间/浓度依赖性表现出一级动力学,其速率取决于催化剂浓度。ln k obs与ln [ZnCl 2 ]的关系图表示使用NMR和UV-vis反应监测,一阶环异构化,即ZnCl 2浓度。丙基呋喃嘧啶核苷的晶体结构(斜方晶系,P 2 1 2 1 2 1,a /