A Generalized Procedure for the One-Pot Preparation of Glycosyl Azides and Thioglycosides Directly from Unprotected Reducing Sugars under Phase-Transfer Reaction Conditions
作者:Rishi Kumar、Pallavi Tiwari、Prakas R. Maulik、Anup K. Misra
DOI:10.1002/ejoc.200500646
日期:2006.1
Per-O-acetylated glycosylazides and thioglycosides were prepared in excellent yield directlyfromunprotectedreducingsugars through in situ generation of per-O-acetylated glycosyl bromides by a generalizedone-potprocedureunderphase-transferconditions. Stereoselective products were formed with complete inversion at the anomeric centers of the glycosyl bromides to provide a general high-yielding
coupling reactions, the oligoamide fragment -Py[R]-γ-Py-Ind has been constructed. The last coupling reaction between the anomeric amino sugar and the oligoamide fragment was carried out by activating the acid derivative as a BtO- ester, which has been performed by using TFFH. The isolated esters (BtO-Py[R]-γ-Py-Ind) were coupled with selected amino sugars using DIEA in DMF. The synthesis of two different
Synthesis of biurets <i>via</i> TMSNCO addition to 1-aminosugars: application in the <i>de novo</i> synthesis of dC oxidation products
作者:Veronika Tsoulougian、Emmanuel E. Psykarakis、Thanasis Gimisis
DOI:10.1039/c8ob02810a
日期:——
and trimethylisocyanate (TMSNCO) was optimised as a one-step synthetic strategy for the synthesis of sugar biurets. This protocol was successfully applied to a number of 1-aminosugars, which exclusively provided the corresponding biurets in 67–99% yields. The new methodology was applied in the denovosynthesis of N1-(2-deoxy-α/β-D-erythro-pentofuranosyl)biuret (dfBU) and N1-(2-deoxy-α/β-D-erythro
1-氨基糖和三甲基异氰酸酯(TMSNCO)之间的反应被优化为一步合成糖缩二脲的合成策略。该方案已成功应用于多种1-氨基糖,它们以67-99%的产率专门提供了相应的缩二脲。新方法是在所施加的从头合成的Ñ 1 - (2-脱氧- α/β- d -赤-pentofuranosyl)缩二脲(dfBU)和Ñ 1 - (2-脱氧- α/β- d -赤-戊吡喃糖基)缩二脲(dpBU),两个已知的DNA损伤是由羟自由基引起的2'-脱氧胞苷(dCyd)分解引起的。
Iron(iii) chloride as an efficient catalyst for stereoselective synthesis of glycosyl azides and a cocatalyst with Cu(0) for the subsequent click chemistry
作者:Santosh B. Salunke、N. Seshu Babu、Chien-Tien Chen
DOI:10.1039/c1cc13370e
日期:——
A highly efficient and mild method for azido glycosylation of glycosyl β-peracetates to 1,2-trans glycosyl azides was developed by using inexpensive FeCl3 as the catalyst. In addition, we demonstrated, for the first time, that FeCl3 in combination with copper powder can promote 1,3-dipolar cycloaddition (click chemistry) of azido glycosides with terminal alkynes. Good to excellent yields were obtained with exclusive formation of a single isomer in both glycosyl azidation and subsequent cycloaddition processes.
bifunctional glutaryl linker. In contrast to caspofungin, these glycosylatedderivatives are soluble in water, but are not hygroscopic and moreover, are more stable than caspofungin under high humidity and temperature. CD studies showed that glycosylation has very little impact on the conformation of the cyclicpeptide of caspofungin. In vitro antifungal tests against seven human pathogenic fungi revealed
近几十年来,由系统性真菌感染引起的疾病已成为重要的临床问题。一系列经批准的环肽抗真菌药物卡泊芬净的共轭与β-的糖基衍生物的d -glucopyranose,β- d -galactopyranose,β- d -xylopyranose,β-大号鼠李糖吡喃糖,β-麦芽糖和β-乳糖单元被设计,合成和评估为新的潜在抗真菌药物。通过将相应的糖基胺通过双功能戊二芳基接头偶联到卡泊芬净的游离伯氨基上而获得化合物。与卡泊芬净相反,这些糖基化衍生物可溶于水,但不吸湿,而且在高湿度和高温下比卡泊芬净更稳定。CD研究表明,糖基化对卡泊芬净环肽的构象影响很小。对七种人类病原真菌的体外抗真菌试验表明,相对于卡泊芬净,卡泊芬净-单糖结合物而非二糖结合物对大多数被测真菌具有更高的抗真菌活性。D-吡喃葡萄糖基衍生物2 a显示出最强和最广泛的抗真菌活性,为进一步的研究提供了线索。