Cubero I I, López-Espinosa M T, Díaz R R, Montalbán F F
Department of Organic Chemistry, Faculty of Pharmacy, University of Granada, Spain.
Carbohydr Res. 2001 Feb 15;330(3):401-8. doi: 10.1016/s0008-6215(00)00319-0.
Either 3-O-benzoyl- (2a) or 3-O-benzyl-1,2-O-isopropylidene-beta-D-fructopyranose (2b) were regioselectively O-benzylated at C-4 to give 4a and 4b, respectively, which were transformed into 5-azido-3-O-benzoyl-4-O-benzyl- (6a) and 5-azido-3,4-di-O-benzyl-5-deoxy-1,2-O-isopropylidene-alpha-L-sorbopyranose (6b) by nucleophilic displacement of the corresponding 5-O-mesyl derivatives 5a and 5b by sodium azide in DMF, respectively. Compound 6b was also prepared from 4b in one step by the Mitsunobu methodology. Deacetonation of 6a and 6b gave the partially protected free azidouloses 8a and 8b, respectively, that were protected as their 1-O-TBDPS derivatives 9a and 9b. Hydrogenation of 9b over Raney nickel gave stereoselectively (2R,3R,4R,5S)-3,4-dibenzyloxy-2'-O-tert-butyldiphenylsilyl-2,5-bis(hydroxymethyl)pyrrolidine (12) which was identified by transformation into the well known (2R,3R,4R,5S)-3,4-dihydroxy-2,5-bis(hydroxymethyl)pyrrolidine (1, DGDP).
3-O-苯甲酰基-（2a）或3-O-苄基-1,2-O-异亚丙基-β-D-呋喃果糖（2b）分别在C-4位进行区域选择性O-苄基化，分别得到4a和4b，它们通过叠氮化钠在DMF中对相应的5-O-甲磺酰基衍生物5a和5b进行亲核取代反应，分别转化为5-叠氮基-3-O-苯甲酰基-4-O-苄基-（6a）和5-叠氮基-3,4-二-O-苄基-5-脱氧-1,2-O-异亚丙基-α-L-山梨吡喃糖（6b）。化合物6b也可通过光延反应方法由4b一步制备。6a和6b的脱乙酰反应分别得到部分保护的游离叠氮糖8a和8b，它们被保护为其1-O-TBDPS衍生物9a和9b。9b在阮内镍上进行氢化反应，立体选择性地得到（2R,3R,4R,5S）-3,4-二苄氧基-2'-O-叔丁基二苯基甲硅烷基-2,5-双（羟甲基）吡咯烷（12），它通过转化为众所周知的（2R,3R,4R,5S）-3,4-二羟基-2,5-双（羟甲基）吡咯烷（1，DGDP）来鉴定。
