"Quantamycin" - a computer-simulated new-generation inhibitor of bacterial ribosomal binding

Practical Gram-Scale Synthesis of Iboxamycin, a Potent Antibiotic Candidate

A gram-scale synthesis of iboxamycin, an antibiotic candidate bearing a fused bicyclic amino acid residue, is presented. A pivotal transformation in the route involves an intramolecular hydrosilylation-oxidation sequence to set the ring-fusion stereocenters of the bicyclic scaffold. Other notable features of the synthesis include a high-yielding, highly diastereoselective alkylation of a pseudoephenamine amide, a convergent sp³-sp² Negishi coupling, and a one-pot transacetalization-reduction reaction to form the target compound's oxepane ring. Implementation of this synthetic strategy has provided ample quantities of iboxamycin to allow for its in vivo profiling in murine models of infection.

First example of 5/6-O-linked pseudosaccharides: synthesis of bicyclic nucleosides containing azido or extended carbohydrate moiety

Treatment of the d-glucose-derived substrate 1 with sodium hydride in tetrahydrofuran provided 3,6-anhydro monosaccharide 2, along with the 5,6-ether linked pseudodisaccharide 3, and pseudotrisaccharide 4. However, reaction of 1 with sodium ethoxide in ethanol afforded 2 as the sole product, elaborated to the bicyclic azidonucleosides 9 and 16. Acetylated bicyclic nucleosides 17-19 with extended carbohydrate residues have been synthesized from 3.

Ring-Modified Analogues and Molecular Dynamics Studies To Probe the Requirements for Fungicidal Activities of Malayamycin A and Its N-Nucleoside Variants

The importance of functional group orientations and the integrity of the bicyclic perhydrofuran core of malayamycin A and two equally active N-nucleoside analogues as fungicides were investigated. Two analogues 10 and 11, representing a THP-truncated and a bicyclic aza-variant, were synthesized and found to be inactive. Molecular dynamics studies on malayamycin A and analogues were performed to highlight the importance of properly orientating the urea and methyl ether groups.

Structure-Based Organic Synthesis of a Tricyclic N-Malayamycin Analogue

The solid-state structure of crystalline malayamycin A reveals a urea substituent that bisects the plane of the chairlike tetrahydropyran subunit. On the basis of this topological feature, we synthesized a tricyclic N-nucleoside analogue in which an ethano bridge linked the urea NH group with the ring junction of the bicyclic tetrahydrofuropyran unit.

Bicyclic carbohydrate-derived scaffolds for combinatorial libraries

A bicyclic scaffold derived from the natural monosaccharide d-glucose, and possessing several diversity sites, was linked to various resins through the primary (C-6) hydroxyl and decorated on the solid phase: the hydroxyl group at C-4 was functionalized as ester, ether, and carbamate, the amino group in the second cycle (C-3' position) was functionalized as amide, sulfonamide, and ureido- and thioureido-derivatives. The compounds synthesized on the solid phase were tested for their antiproliferative activity on tumor cell lines.

3-N,N-Dimethylamino-3-deoxy lincomycin: A structure-based hybrid between lincomycin and the desosamine unit of erythromycin

The observation that the desosamine sugar unit in erythromycin and the methyl thiolincosaminide portion of lincomycin occupy virtually identical sites on the 23S rRNA according to X-ray crystallograpaic data, instigated the synthesis of 3-N,N-dimethylamino-3-deoxy lincomycin as a hybrid structure. The synthesis in eight steps from lincomycin, involving a trans-diequatorial opening of an intermediate epoxide as the key step, is described.

Total Synthesis of N-Malayamycin A and Related Bicyclic Purine and Pyrimidine Nucleosides

Methods are described for the total synthesis of bicyclic perhydrofuropyran nucleosides as N-analogues of the naturally occurring malayamycin A. Formation of the N-nucleosides relied on the activation of thioglycosides, proceeding via sulfonium intermediates. Ring closure metathesis was used in two approaches to build the bicyclic dioxa heterocycle. Another approach relied on the use of a sugar precursor and cyclization to the bicyclic thioglycoside.

Total Synthesis and Structural Confirmation of Malayamycin A: A Novel BicyclicC-Nucleoside fromStreptomycesmalaysiensis

[reaction: see text] The stereocontrolled synthesis of malayamycin A, a novel naturally occurring bicyclic C-nucleoside of the perhydrofuropyran type, is described.

Antibiotic inhibitors of the peptidyl transferase center. 1. Clindamycin as a composite analogue of the transfer RNA fragments L-Pro-Met and the D-ribosyl ring of adenosine

Clindamycin's three-dimensional structure is shown via a computer rendered stereomodel to be strikingly similar to L-Pro-Met and the D-ribosyl ring of adenosine. This discovery has important implications for the rational design of new licosamides and for efforts to understand how this and related classes of agents selectively inhibit protein biosynthesis on the prokaryotic ribosome.

An asymmetric approach to 2-deoxynucleosides via organosulfur building blocks as chemical chameleons

An asymmetric synthesis of 6-N-benzoyl-5'-O-benzyl-2'-deoxyadenosine and its a anomer from non-carbohydrate building blocks is achieved in 7 steps. The sequence builds the basic structures using bis(methylthio)methane and methylthiomethyl phenyl sulfone as both nucleophilic and electrophilic building blocks, a feature that suggests their behavior as chemical chameleons. The asymmetric induction is achieved utilizing a kinetic resolution based upon catalytic asymmetric epoxidation.

Palladium(0)-assisted synthesis of C-glycopyranosyl compounds

Tetrakis(triphenylphosphine)palladium(0) effects the regio- and stereo-selective alkylation of 2-acetoxy-5,6-dihydro-2H-pyrans and 1-S-acetyl-1-thiohex-2-enopyranosides. Use of stabilized carbanions resulted in the formation of alkylated dihydropyrans with net retention at the oxygen-bearing carbon atom. Examples include the preparation of 2-[acetamidobis(ethoxycarbonyl)methyl]-5,6-dihydro-2H-pyran, 2-[acetamidobis(methoxycarbonyl)methyl]-6-ethoxy-5,6-dihydro-2H-py ran, and 2-[acetamidobis(methoxycarbonyl)methyl]-6-methoxymethyl-5,6-dihydr o-2H- pyran. Use of nonstabilized carbanions, such as arylzinc chlorides, resulted in the formation of alkylated dihydropyrans and C-glycosyl compounds with net inversion at the oxygen-bearing carbon atom. Examples include the preparation of 2-[(6-ethoxy-5,6-dihydro-2H-pyranyl)methyl]-4,4-dimethyl-2-oxazoli ne, trans-methoxymethyl-2-phenyl-5,6-dihydro-2H-pyran, trans-methoxymethyl-2-vinyl-5,6-dihydro-2H-pyran, trans-2-[2,2-bis(ethoxy)ethyl]-6-methoxymethyl-5,6-dihydro-2H-pyran, (4,6-di-O-methyl-2,3-dideoxy-alpha-D-erythro-hex-2-enopyranosyl)be nzene, (2,3-dideoxy-4,6-di-O-methyl-beta-D-erythro-hex-2-enopyranosyl)ben zene, 1-(2,3-dideoxy-4,6-di-O-methyl-alpha and -beta-D-erythro-hex-2-enopyranosyl)naphthalene, 4-(2,3-dideoxy-4,6-di-O-methyl-alpha- and -beta-D-erythro-hex-2-enopyranosyl)toluene, and 1-(2,3-trideoxy-4-O-methyl-alpha-L-erythro-hex-2-enopyranosyl)naph thalene.