Metal-Free Deprotection of Terminal Acetonides by Using tert-Butyl Hydroperoxide in Aqueous Medium
作者:Kandikere Prabhu、Mahagundappa Maddani
DOI:10.1055/s-0030-1259917
日期:2011.4
as an inexpensive reagent a useful methodology for the regioselective and chemoselective deprotection of terminal acetonide groups in aqueous medium is developed. A variety of acetonide derivatives on reaction with aqueous tert-butyl hydroperoxide in water:tert-butanol (1:1) furnish the corresponding acetonide deprotected diols in good yields. A large number of acid labile protecting functional groups
efficient, stereoselective and short approach for the total syntheses of some carbahexopyranoses namely, MK7607, (−)-gabosine A, (−)-conduritol E, (−)-conduritol F, 6a-carba-β-D-fructopyranose and other carbasugars using chemoselective Grignard or Nozaki–Hiyama–Takai–Kishi (NHTK) reactions and RCM. Herein, the Grignard and NHTK reactions are able to differentiate the reactivity difference between lactol
一种通用、发散、高效、立体选择性和简短的方法,用于全合成某些吡喃碳糖,即 MK7607、(−)-gabosine A、(−)-conduritol E、(−)-conduritol F、6a-carba-β- D -吡喃果糖和其他卡巴糖,使用化学选择性格氏反应或野崎-桧山-高井-岸 (NHTK) 反应和 RCM。在此,格氏反应和NHTK反应能够在给定条件下区分乳醇或乳醇乙酸酯与醛2和6之间的反应性差异,以给出所需的骨架化学选择性。
Zeolite catalyzed selective deprotection of di- and tri-O-isopropylidene sugar acetals
H-Beta zeolite, a microporous solid acid, is demonstrated to be an efficient catalyst for the selective deprotection of cyclic as well as acyclic O-isopropylidene sugar acetals derived from D-glucose, D-xylose, D-mannose, and D-mannitol in aqueous MeOH at room temperature. A notable observation is the conversion Of D-mannitol triacetonide into 1,2:3,4-di-O-isopropylidene-D-mannitol (48%) and 3,4-O-isopropylidene-D-mannitol (36%) brought about in 6 h by H-beta zeolite and the non-occurrence of any hydrolysis in the case of H-ZSM-5 catalyzed reaction in 24 h under the same conditions. (c) 2008 Elsevier Ltd. All rights reserved.
Réaction du diméthyl(diazométhyl)phosphonate sur des glucides réducteurs: synthèse de glyco-1-ynitols
Reaction of aldose derivatives with dimethyl(diazomethyl)phosphonate, generated in situ by methanolysis of dimethyl(1-diazo-2-oxopropyl)phosphonate leads to glyco-1-ynitols derivatives. This synthesis presents two main advantages: it is a one-step synthesis, and tolerates free hydroxyl groups. (C) 2000 Elsevier Science Ltd. All rights reserved.
Stereochemical control in the formation of thiazolidines from O-protected reducing sugars
作者:Anne Wadouachi、Daniel Beaupere、Raoul Uzan、Imane Stasik、David F. Ewing、Grahame Mackenzie