Whole in one! A one-pot microwave-assisted reaction sequence that consists of an Ugi/Michael/aza-Michael transformation gives access to quaternary spirocenters leading Amaryllidaceae and Erythrina alkaloid like compounds (see scheme). The process produces four stereogenic centers six contiguous bonds, provides products with good excellent yields appreciable diastereoselectivity.

With a view to reducing the notorious complexity and irreproducibility of glycosylation reactions, 12 guidelines for choice concentration, temperature, counterions are adumbrated.

A catalytic asymmetric Passerini reaction using tridentate indan (pybox) Cu(II) Lewis acid complex 4 with substrates capable of bidentate coordination has been achieved. The occurs via ligand-accelerated catalysis.

An entirely carbohydrate-based immunogen consisting of a zwitterionic polysaccharide (ZPS) PS A1 and the well-known tumor antigen Tn has been designed, synthesized, studied for immunological effects. The motif was included to act as an MHCII elicitor T-cell-dependent immune response with increased immunogenicity against tumor-associated carbohydrate antigens, providing alternative carrier proteins. Through use C57BL/6 mice, it shown that chemical modification does not alter recognition...

Small molecule diversity can be achieved in a single synthetic operation from bifunctional substrates the absence of additives and under influence microwaves with complete control pathway selectivity. The preliminary Ugi four-component coupling products give rise to three structurally distinct scaffolds that are dependent on solvent effects sterics. 2,5-Diketopiperazines (Type A), 2-azaspiro[4.5]deca-6,9-diene-3,8-diones B), thiophene-derived Diels-Alder tricyclic lactams C) predominate this...

A one-pot, two-step synthesis of the title compounds employs a multicomponent Ugi condensation reaction, microwave irradiation, and Fe(0) as reductant. Two pathways are accessible; both routes utilize bifunctional, o-nitro-substituted arenes leading to either C2, N4, C5 substitution (A) or N4 (B).

Sialyl Thomsen-nouveau (STn) is a tumor-associated carbohydrate antigen (TACA) that overexpressed in variety of carcinomas such as breast, ovarian, and colon cancer. In normal tissue, STn not detectable, which critical for opportunities developing cancer immunotherapies. A novel, entirely carbohydrate, semisynthetic STn-polysaccharide (PS) A1 conjugate was prepared evaluated C57BL/6 mice. STn-PS combined with commercially available monophosphoryl lipid A-based adjuvant, after immunization,...

Substrates having appendages that pre-encode skeletal information (σ-elements) can be converted into products distinct skeletons using a common set of reaction conditions. The sequential use the Ugi 4CC-IMDA reaction, followed by allylation, hydrolysis, and acylation chiral amino alcohol appendage (σ-element), leads to substrates for ROM/RCM or RCM reaction. stereochemistry σ-element not its constitution controls outcome pathway selected. This work illustrates potential linking...

Grubbs' RuCl2(CHPh)(PCy3)2 (catalyst 1) and RuCl2(CHPh)(PCy3)(IMess) 2) complexes have been successfully utilized in the construction of β,γ-unsaturated δ-lactones containing various substitution patterns methyl groups. Asymmetric dihydroxylation followed by reduction leads to 3,4-cis-dihydroxy-2,6-dideoxypyranoses, which proven play very important biological roles as key components natural products.

A rapid, cascade reaction process has been developed to access biologically validated spiro-2,5-diketopiperazines. The facile and environmentally benign method capitalizes on commercially available starting reagents for a sequential Ugi/6-exo-trig aza-Michael reaction, water as solvent, microwave irradiation without any extraneous additives.

The α-aminooxy derivative of the Thomsen–Friedenriech tumor-associated carbohydrate antigen has been synthesized in 11 steps. This nucleophilic sugar was then utilized preparation TF-PS A1 conjugate vaccine candidate through oxime bond formation.

The tetrasaccharide repeating unit of zwitterionic polysaccharide A1 (PS A1) from Bacteroides fragilis ATCC 25285/NCTC 9343 has been synthesized using a linear glycosylation approach. One key step includes an α(1,4)-stereoselective [2 + 1] 2,4,6-trideoxy-2-acetamido-4-amino-d-Galp (AAT) donor with poorly reactive axial C4-OH disaccharide acceptor. Mild acid-mediated deacetylation and challenging [3 are also highlighted. strategy is inclusive single-pot, three-step deprotection affording PS...

The herbicide (±)-thaxtomin A has been synthesized in a one-pot two step process through an Ugi reaction followed by base-mediated cyclization.

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTTransferring a Biosynthetic Cycle into Productive Escherichia coli Strain: Large-Scale Synthesis of GalactosidesXi Chen, Jianbo Zhang, Przemek Kowal, Ziye Liu, Peter R. Andreana, Yuquan Lu, and Peng George WangView Author Information Department Chemistry, Wayne State University Detroit, Michigan 48202 Cite this: J. Am. Chem. Soc. 2001, 123, 36, 8866–8867Publication Date (Web):August 17, 2001Publication History Received12 May 2001Revised13...

The synthesis of a small library differentially-linked β-C-disaccharides has been carried out through the use radical allylation-RCM strategy. Acids 6 were prepared by Keck allylation suitable carbohydrate-based precursor, followed oxidative cleavage formed alkene. Dehydrative coupling these acids with known olefin alcohol 5 then gave precursor esters 7 in excellent yield. Methylenation was RCM and situ hydroboration−oxidation glycals to furnish protected 10 good overall Five examples...

Reaktionskaskade: Eine mikrowellenunterstützte Sequenz aus Ugi-, Michael- und Aza-Michael-Reaktion führt zu quartären Spirozentren Amaryllidaceae- Erythrina-Alkaloid-artigen Verbindungen (siehe Schema). Die erzeugt vier stereogene Zentren sechs benachbarte Bindungen; die Produkte werden diastereoselektiv in guten bis exzellenten Ausbeuten erhalten.