01454nas a2200253 4500008004100000022001400041245009200055210006900147260010600216300001400322490000700336520052200343653001300865653001500878653002000893653001600913653002200929100003000951700002200981700002601003700002301029700003101052856011701083 2007 eng d a0040-402000aStereoselective synthesis of 3-alkylidene/alkylazetidin-2-ones from azetidin-2,3-diones0 aStereoselective synthesis of 3alkylidenealkylazetidin2ones from  aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLANDbPERGAMON-ELSEVIER SCIENCE LTDcMAR a2524-25340 v633 a

Azetidin-2,3-diones have been used as synthons for the synthesis of C-3 alkylidene/alkylazetidin-2-ones. Some of the 3-alkylazetidin-2-ones are well known for their cholesterol absorption inhibitor activity. A regio and stereoselective Grignard reaction on a keto group followed by dehydration using PPh3/CCl4 reagent is a key step in this synthesis. Hydrogenation of the 3-alkylideneazetidin-2-ones provided stereoselectively cis-3-alkylazetidin-2-ones in very good yields. (c) 2006 Published by Elsevier Ltd.

10a3-diones10aazetidin-210aazetidin-2-ones10abeta-lactam10aGrignard reaction1 aTiwari, Dharmendra, Kumar1 aShaikh, Ashif, Y.1 aPavase, Laxmikant, S.1 aGumaste, Vikas, K.1 aDeshmukh, Abdul, Rakeeb A. uhttps://library.ncl.res.in/content/stereoselective-synthesis-3-alkylidenealkylazetidin-2-ones-azetidin-23-diones01469nas a2200193 4500008004100000022001400041245012800055210006900183260011000252300001400362490000600376520065800382100002201040700002701062700001901089700002201108700002001130856012501150 2011 eng d a1477-052000aFacile synthesis of unusual glycosyl carbamates and amino acid glycosides from propargyl 1,2-orthoesters as glycosyl donors0 aFacile synthesis of unusual glycosyl carbamates and amino acid g aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcMAR a5951-59590 v93 a

Propargyl 1,2-O-orthoesters are exploited for the synthesis of 1,2-trans O-glycosides of protected amino acids. N-Fmoc- and N-Cbz protected serine/threonine - benzyl/methyl esters reacted well with glucosyl-, galactosyl-, mannosyl- and lactosyl- derived propargyl 1,2-orthoesters affording respective 1,2-trans glycosides in good yields under AuBr(3)/4 angstrom MS Powder/CH(2)Cl(2)/rt. t-Boc serine derivative gave serine 1,2-orthoester and glycosyl carbamate. Optimized conditions enabled preparation of new glycosyl carbamates from N-Boc protected amines in a single step using gold catalysts and propargyl 1,2-orthoesters in excellent yields.

1 aShaikh, Ashif, Y.1 aSureshkumar, Gopalsamy1 aPati, Debasish1 aGupta, Sayam, Sen1 aHotha, Srinivas uhttps://library.ncl.res.in/content/facile-synthesis-unusual-glycosyl-carbamates-and-amino-acid-glycosides-propargyl-12-001420nas a2200181 4500008004100000022001400041245013000055210006900185260011000254300001200364490000600376520064300382100001801025700002201043700002001065700002201085856013101107 2011 eng d a1759-995400aSynthesis of glycopolypeptides by the ring opening polymerization of O-glycosylated-alpha-amino acid N-carboxyanhydride (NCA)0 aSynthesis of glycopolypeptides by the ring opening polymerizatio aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcFEB a805-8110 v23 a

The novel synthesis of O-glycosylated lysine-NCA from a stable glycosyl donor and a commercially available protected amino acid in very high yield is reported. These O-glycosylated lysine-NCA monomers underwent ring opening polymerization using simple primary amine initiators to form well defined, high molecular weight homoglycopolypeptides and diblock co-glycopolypeptides. The synthesis of azide labelled end functionalized glycopolypeptides and amphiphilic diblock copolypeptides is also reported. This methodology represents an easy and practical route to the synthesis of O-glycosylated polypeptides with 100% glycosylation.

1 aPati, Debasis1 aShaikh, Ashif, Y.1 aHotha, Srinivas1 aGupta, Sayam, Sen uhttps://library.ncl.res.in/content/synthesis-glycopolypeptides-ring-opening-polymerization-o-glycosylated-alpha-amino-acid-n-002126nas a2200217 4500008004100000022001400041245009900055210006900154260007100223300001400294490000700308520131800315100001801633700002201651700001601673700002601689700002101715700002001736700002201756856013001778 2012 eng d a1525-779700aControlled synthesis of O-glycopolypeptide polymers and their molecular recognition by lectins0 aControlled synthesis of Oglycopolypeptide polymers and their mol a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcMAY a1287-12950 v133 a

The facile synthesis of high molecular weight water-soluble O-glycopolypeptide polymers by the ring-opening polymerization of their corresponding N-carboxyanhydride (NCA) in very high yield (overall yield > 70%) is reported. The per-acetylated-O-glycosylated lysine-NCA monomers, synthesized using stable glycosyl donors and a commercially available protected amino acid in very high yield, was polymerized using commercially available amine initiators. The synthesized water-soluble glycopolypeptides were found to be alpha-helical in aqueous solution. However, we were able to control the secondary conformation of the glycopolypeptides (alpha-helix vs nonhelical structures) by polymerizing raceznic amino acid glyco NCAs. We have also investigated the binding of the glycopolypeptide poly(alpha-manno-O-lys) with the lectin Con-A using precipitation and hemagglutination assays as well as by isothermal titration calorimetry (ITC). The ITC results clearly show that the binding process is enthalpy driven for both alpha-helical and nonhelical structures, with negative entropic contribution. Binding stoichiometry for the glycopolypeptide poly(alpha-manno-O-lys) having a nonhelical structure was slightly higher as compared to the corresponding polypeptide which adopted an alpha-helical structure.

1 aPati, Debasis1 aShaikh, Ashif, Y.1 aDas, Soumen1 aNareddy, Pavan, Kumar1 aSwamy, Musti, J.1 aHotha, Srinivas1 aGupta, Sayam, Sen uhttps://library.ncl.res.in/content/controlled-synthesis-o-glycopolypeptide-polymers-and-their-molecular-recognition-lectins-002087nas a2200193 4500008004100000022001400041245006800055210006700123260007100190300001400261490000700275520140500282100002001687700002201707700002001729700002001749700002201769856010201791 2013 eng d a0743-746300aSynthesis and self-assembly of amphiphilic homoglycopolypeptide0 aSynthesis and selfassembly of amphiphilic homoglycopolypeptide a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcMAY a5659-56670 v293 a

The synthesis of the amphiphilic homoglycopolypeptide was carried out by a combination of NCA polymerization and click chemistry to yield a well-defined Polypeptide having an amphiphilic carbohydrate on its side chain. The amphiphilicity of the carbohydrate was achieved by incorporation of an alkyl chain, at the C-6 position of the carbohydrate thus also rendering the homoglycopolypeptide amphiphilic. The homoglycopolypeptide formed multimicellar aggregates in water above a critical concentration of 0.9 mu M due to phase separation. The multimicellar aggregates were characterized by DLS, TEM, and AFM. It is proposed that hydrophobic interactions of the aliphatic chains at the 6-position of the sugar moieties drives the assembly of these rod-like homoglycopolypeptide into large;spherical aggregates. These multimicellar aggregates encapsulate both hydrophilic as well as hydrophobic dye as was confirmed by confocal microscopy. finally, amphiphilic random polypeptides containing 10% and 20% alpha-D-mannose in addition to glucose containing a, hydrophobic alkyl chain at its 6 position were synthesized by our methodology, and these polymers Were also found to assemble into spherical nanostructures. The spherical assemblies Of amphiphilic random glycopolypeptides containing 10% and 20% mannose were found to be surface bioactive and were found, to interact with the lectin Con-A.

1 aDhaware, Vinita1 aShaikh, Ashif, Y.1 aKar, Mrityunjoy1 aHotha, Srinivas1 aGupta, Sayam, Sen uhttps://library.ncl.res.in/content/synthesis-and-self-assembly-amphiphilic-homoglycopolypeptide-002237nas a2200205 4500008004100000022001400041245012400055210006900179260007100248300001400319490000700333520144600340100002201786700001601808700001801824700002001842700002201862700002001884856012701904 2014 eng d a1525-779700aCationic charged helical glycopolypeptide using ring opening polymerization of 6-deoxy-6-azido-glyco-N-carboxyanhydride0 aCationic charged helical glycopolypeptide using ring opening pol a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcOCT a3679-36860 v153 a

Glycopolypeptides with a defined secondary structure are of significance in understanding biological phenomena. Synthetic glycopolypeptides, or polypeptides featuring pendant carbohydrate moieties, have been of particular interest in the field of tissue engineering and drug delivery. In this work, we have synthesized charged water-soluble glycopolypeptides that adopt a helical conformation in water. This was carried out by the synthesis of a glyco-N-carboxyanhydride (glyco-NCA) containing an azide group at the sixth position of the carbohydrate ring. Subsequently, the NCA was polymerized to obtain azide-containing glycopolypeptides having good control over molecular weight and polydispersity index (PDI) in high yields. We were also able to control the incorporation of the azide group by synthesizing random co-glycopolypeptide containing 6-deoxy-6-azido and regular 6-OAc functionalized glucose. This azide functionality allows for the easy attachment of a bioactive group, which could potentially enhance the biological activity of the glycopolypeptide. We were able to obtain water-soluble charged glycopolypeptides by both reducing the azide groups into amines and using CuAAC with propargylamine. These charged glycopolypeptides were shown to have a helical conformation in water. Preliminary studies showed that these charged glycopolypeptides showed good biocompatibility and were efficiently taken up by HepG2 cells.

1 aShaikh, Ashif, Y.1 aDas, Soumen1 aPati, Debasis1 aDhaware, Vinita1 aGupta, Sayam, Sen1 aHotha, Srinivas uhttps://library.ncl.res.in/content/cationic-charged-helical-glycopolypeptide-using-ring-opening-polymerization-6-deoxy-6-0