Aptamer protective groups tolerate different reagents and reactions for regioselective modification of neomycin B

2020 ◽  
Vol 18 (47) ◽  
pp. 9606-9610
Author(s):  
Andreas A. Bastian ◽  
Agnieszka Gruszka ◽  
Philippe Jung ◽  
Andreas Herrmann
Keyword(s):  
Protective Group ◽  
Reaction Conditions ◽  
Group Strategy ◽  
Protective Groups ◽  
Neomycin B ◽  
Regioselective Modification

The aptameric protective group strategy is compatible with diverse reagents and reaction conditions for the synthesis of new neomycin B derivatives.

Azidation of Partially Protected Carbohydrate Derivatives: Efficient Suppression of Acyl Migration

Synlett ◽  
2020 ◽  
Vol 31 (15) ◽  
pp. 1491-1496
Author(s):  
Leonid O. Kononov ◽  
Elena V. Stepanova ◽  
Alexander I. Zinin ◽  
Polina I. Abronina ◽  
Alexander O. Chizhov
Keyword(s):  
Organic Chemistry ◽  
Phase Transfer ◽  
Acyl Migration ◽  
Hydroxyl Group ◽  
Azido Group ◽  
Protective Group ◽  
Reaction Conditions ◽  
Free Hydroxy Group ◽  
Efficient Suppression ◽  
Protective Groups

Although azidation by nucleophilic substitution is widely used in organic chemistry, it has a limitation for partially protected carbohydrate derivatives under typical reaction conditions used for azidation (heating with NaN3, phase-transfer catalyst (optional), DMF or DMSO) as it can cause substantial migration (70%) of O-acyl protective groups. Several approaches, including the use of a temporary protective group for the unprotected hydroxyl group, to avoid acyl migration have been compared. Addition of excess of ethyl trifluroacetate effectively suppressed benzoyl migration but inhibited substitution of the chlorine atom with the azido group. The most robust procedure involved addition of excess n-butyl formate to the reaction mixture. When this protocol was followed, migration of benzoyl groups in lactose derivatives with free hydroxy group at C-3′ or C-4′ was reduced to 4%, with the yield of the target, partially protected derivatives with an azido group in the aglycone approaching 92%.

scholarly journals Application of the N-Dibenzyl Protective Group in the Preparation of β-Lactam Pseudopeptides

Molecules ◽  
2019 ◽  
Vol 24 (7) ◽  
pp. 1261
Author(s):  
Rok Frlan ◽  
Martina Hrast ◽  
Stanislav Gobec
Keyword(s):  
Mitsunobu Reaction ◽  
Successful Implementation ◽  
Protective Group ◽  
Reaction Conditions ◽  
Protective Groups ◽  
High Yields ◽  
Synthetic Approaches

Despite the great importance of β-lactam antibiotics, there is still a limited number of synthetic approaches for the formation of β-lactam–containing dipeptides. In this study, we report upon the stereoselective preparation of β-lactam–containing pseudopeptides, where different reaction conditions and NH2 protective groups were tested to obtain compounds that contain 3-amino-azetidin-2-one. We demonstrate that the protective group is essential for the outcome of the reaction. Successful implementation of dibenzyl-protected serine-containing dipeptides through the Mitsunobu reaction can provide the desired products at high yields and stereoselectivity.

A Facile, Efficient and Selective Deprotection of P - Methoxy Benzyl Ethers Using Zinc (II) Trifluoromethanesulfonate

2019 ◽  
Vol 16 (12) ◽  
pp. 955-958
Author(s):  
Reddymasu Sireesha ◽  
Reddymasu Sreenivasulu ◽  
Choragudi Chandrasekhar ◽  
Mannam Subba Rao
Keyword(s):  
Room Temperature ◽  
Protecting Groups ◽  
Side Reactions ◽  
Reaction Conditions ◽  
Acid Sensitivity ◽  
Time Period ◽  
Protective Groups ◽  
Benzyl Ethers ◽  
Last Stage ◽  
Zinc Triflate

: Deprotection is significant and conducted over mild reaction conditions, in order to restrict any more side reactions with sensitive functional groups as well as racemization or epimerization of stereo center because the protective groups are often cleaved at last stage in the synthesis. P - Methoxy benzyl (PMB) ether appears unique due to its easy introduction and removal than the other benzyl ether protecting groups. A facile, efficient and highly selective cleavage of P - methoxy benzyl ethers was reported by using 20 mole% Zinc (II) Trifluoromethanesulfonate at room temperature in acetonitrile solvent over 15-120 min. time period. To study the generality of this methodology, several PMB ethers were prepared from a variety of substrates having different protecting groups and subjected to deprotection of PMB ethers using Zn(OTf)2 in acetonitrile. In this methodology, zinc triflate cleaves only PMB ethers without affecting acid sensitivity, base sensitivity and also chiral epoxide groups.

Silylated Sugars – Synthesis and Properties

Synlett ◽  
2021 ◽  
Author(s):  
Mikael Bols ◽  
Tobias Gylling Frihed ◽  
Martin Jæger Pedersen ◽  
Christian Marcus Pedersen
Keyword(s):  
Protective Group ◽  
Carbohydrate Chemistry ◽  
Sugar Alcohols ◽  
Protective Groups ◽  
Silyl Groups ◽  
Conformational Alteration ◽  
Glycosyl Donors

AbstractSilicon has been used in carbohydrate chemistry for half a century, but mostly as a protective group for sugar alcohols. Recently, the use of silicon has expanded to functionalization via C–H activation, conformational arming of glycosyl donors, and conformational alteration of carbohydrates. Silicon has proven useful as more than a protective group and during the last one and a half decades we have demonstrated how it influences both the reactivity of glycosyl donors and stereochemical outcome of glycosylations. Silicon can also be attached directly to the sugar C-backbone, which has even more pronounced effects on the chemistry and properties of the molecules. In this Account, we will give a tour through our work involving silicon and carbohydrates.1 Introduction2 Conformational Arming of Glycosyl Donors with Silyl Groups3 Silyl Protective Groups for Tethering Glycosyl Donors4. Si–C Glycosides via C–H Activation4.1 C–H Activation and Oxidation of Methyl 6-Deoxy-l-glycosides4.2 Synthesis of All Eight 6-Deoxy-l-sugars4.3 Synthesis of All Eight l-Sugars by C–H Activation4.4 Modification of the Oxasilolane Ring5 C–Si in Glycosyl Donors – Activating or Not?6 Si–C-Substituted Pyranosides7 Perspective

Introduction of a substituent at the 5″-position of N-Boc neomycin B under Mitsunobu reaction conditions

2005 ◽  
Vol 3 (11) ◽  
pp. 2064 ◽  
Author(s):  
Angelica Hernandez Linares ◽  
Dominique Fourmy ◽  
Jean-Louis Fourrey ◽  
Ali Loukaci
Keyword(s):  
Mitsunobu Reaction ◽  
Reaction Conditions ◽  
Neomycin B

Synthesis of a Disaccharide with a Thiol Spacer Used in Gold Nanoparticles

2013 ◽  
Vol 643 ◽  
pp. 153-156 ◽  
Author(s):  
Chao Wang
Keyword(s):  
Gold Nanoparticles ◽  
Cell Surface ◽  
Reductive Amination ◽  
Surface Interactions ◽  
Protective Group ◽  
Subsequent Removal ◽  
Satisfactory Yield ◽  
Protective Groups ◽  
Glycosyl Donor ◽  
Cell Surface Interactions

The synthesis of a mannose-bearing disaccharide containing a thiol spacer at the reducing end was carried out to provide a tethered sugar suitable for attaching to gold nanoparticles. Such sugar is designed to mimic carbohydrates involved in cell-surface interactions. The molecule was constructed via Schmidt glycosylation of an appropriately protected glycosyl donor and an acceptor, followed by removal of protective groups and reductive amination to introduce a protected thiol spacer at the reducing end of the glycan. Subsequent removal of the thiol protective group gave the target disaccharide in a satisfactory yield.

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