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Journals and Conferences
Abstract: A facile, 1,3-dipolar cycloaddition of ethyl diazoacetate (EDA) with various activated olefins including Baylis-Hillman adducts, activated and simple alkynes to afford 3,5-disubstituted pyrazolines and pyrazoles respectively in moderate to good yields, in high regioselective manner in the presence of Indium chloride and/or DABCO is reported. All… (More)
The C-linked carbo-beta-peptides, oligomers of a new class of C-linked carbo-beta3-amino acids, have been shown to generate mixed 12/10 and 10/12 helices. The design involves use of "alternating chirality" of the epimeric (at the amine center) monomers to control the stability of these helices. The observation of stable 12/10 helix in a tripeptide and 10/12… (More)
The preparation of chiral tetrahydropyridine-4-carboxylates as isoguvacine analogues and azasugars with a tertiary stereocenter from L-amino acids via diastereoselective a Baylis-Hillman reaction of N-allyl-Boc alpha-aminal, followed by ring-closing metathesis and dihydroxylation sequences, is reported.
A versatile protocol for the production of sugar-linked alpha,beta-unsaturated gamma-lactones with stereochemical and functional group diversity is described starting from sugar-derived Baylis-Hillman adducts via ring-closing metathesis.
Glycopyranosiduronic acids, amidically linked to amino acids (alanine, serine, threonine, and lysine) were prepared.O-tert-Butyl andNε-tert-butyloxycarbonyl protected amino acidtert-butyl esters were used in ethyl 2-ethoxy-1,2-dihydroquinoline-1-carboxylate promoted condensation with 2-azidoethyl glycosides of glucuronic and galacturonic acid. Reduction of… (More)
Electrospray tandem mass spectrometry was used to study the dissociation reactions of [M+Cat]+ (Cat = Na+ and Li+) of Boc-carbo-beta3-peptides. The collision-induced dissociation (CID) spectra of [M+Cat-Boc]+ of these peptides are found to be significantly different from those of [M+H-Boc]+ ions. The spectra are more informative and display both C- and… (More)
The first diastereoselective intramolecular Baylis-Hillman reaction of chiral substrates is reported wherein both aldehyde and activated olefin coexist as substituents to afford alpha-methylene-beta-hydroxylactones in good yields exclusively as single isomers under the standard base-catalyzed reaction conditions in CH(2)Cl(2). Formation of alkoxylactones by… (More)
A highly selective and efficient method for the unmasking of p-methoxybenzyl (PMB) ethers and esters has been developed by use of 20 mol % of zirconium(IV) chloride as Lewis acid in acetonitrile. The present method is very fast, and the conditions are tolerable to a variety of acid/base-sensitive protecting groups and substrates such as carbohydrates,… (More)