Complex Peptidyl Nucleoside Antibiotics: Efficient Syntheses of the Glycosyl Nucleoside Amino Acid Cores

Solving the Structural Puzzles of Amipurimycin and Miharamycins Enabled by Stereodivergent Total Synthesis

The efforts toward the synthesis of amipurimycin and miharamycin A/B, two peptidyl nucleoside antibiotics bearing a unique nine carbon C3-branched pyranosyl amino acid core, are accounted. Highlighted is our stereodivergent total synthesis of all the possible diastereoisomers of amipurimycin, which has enabled us to solve the structural puzzles of amipurimycin and miharamycin A/B after ∼50 years of their discovery.

Theoretical investigation of the chiral transition of serine and the roles of water, hydroxyl radical and hydroxide ion

The serine chiral transition and the roles of water, hydroxyl radical and hydroxide ion as catalysts were theoretically investigated.

Synthesis of the C8'-epimeric thymine pyranosyl amino acid core of amipurimycin

The C8'-epimeric pyranosyl amino acid core 2 of amipurimycin was synthesized from D-glucose derived alcohol 3 in 13 steps and 14% overall yield. Thus, the Sharpless asymmetric epoxidation of allyl alcohol 7 followed by trimethyl borate mediated regio-selective oxirane ring opening with azide, afforded azido diol 10. The acid-catalyzed 1,2-acetonide ring opening in 10 concomitantly led to the formation of the pyranose ring skeleton to give 2,7-dioxabicyclo[3.2.1]octane 12. Functional group manipulation in 12 gave 21 that on stereoselective β-glycosylation afforded the pyranosyl thymine nucleoside 2 - a core of amipurimycin.

Studies on peptidyl nucleoside antibiotics: synthesis and antifungal evaluation of pyranosyl nucleoside analogs of nikkomycin

Background: The Streptomyces-derived nikkomycins are a unique class of peptidyl nucleoside natural products, with potent antifungal activity against a variety of pathogenic fungi. Results: In continuation of our structure–activity relationship studies on the nikkomycins, this paper describes the strategic design, synthesis and biological evaluation of a ‘doubly modified’ generation of nikkomycin analogs. The structural modifications included a ring-expanded carbohydrate core and a simplified peptidyl side chain. Biological screening of these novel analogs against clinical isolates of various human pathogenic fungi indicated that the described modifications of the structural features of nikkomycin could be a potentially beneficial strategy towards optimizing the antifungal potency of this class of peptidyl nucleoside antibiotics. Conclusion: Continued investigation of the pyranosyl nikkomycin analogs is warranted to fully explore and optimize the structural features of this novel lead for the desired development of a new class of therapeutically useful antifungal drugs.

A rapid synthetic route to conformationally restricted [5,5]-bicyclic nucleoside-amino acid conjugates

A concise synthetic route to a novel class of conformationally rigid 3',4'-cis-fused bicyclic nucleoside derivatives has been developed. The synthetic strategy and approach involves initial synthesis of a key [5,5]-bicyclic 6-aminofurofuran-2-one scaffold, employing an L-serine derived aminobutenolide as a strategically functionalized chiral template. Subsequent utilization of the carbonyl functionality of the above bicyclic lactone toward nucleobase incorporation, and linking of the resident amine functionality with appropriately protected amino acids completed the syntheses of the target bicyclic nucleoside-amino acid conjugates. Following the above route, and utilizing a combination of easily available nucleobases (4) and amino acids (4) as the two diversity elements, combinatorial synthesis of a 16-member demonstration library of the title amino acid-linked nucleosides has been accomplished.

Stereoselective synthesis of jaspine B from d-xylose

The natural cytotoxic marine compound, jaspine B, is stereoselectively synthesized from D-xylose in 11 linear steps with a 23.9% overall yield. The key step in the synthesis involves an iodine-induced debenzylation of a primary alcohol and the subsequent 2,5-cyclization to fit the required configuration of jaspine B. A preliminary bioassay shows strong inhibition activities against human MDA231, Hela, and CNE cell lines, indicating potential usage in various cancer treatments.

Stereoselective synthesis of cytotoxic anhydrophytosphingosine pachastrissamine (jaspine B) from D-xylose

The first naturally occurring anhydrophytosphingosine, pachastrissamine (jaspine B), a marine compound cytotoxic toward P388, A549, HT29, and MEL28 cell lines at IC(50) = 0.01 microg/mL level, has been stereoselectively synthesized from D-xylose in 10 linear steps with 25.7% overall yield.

Stereoselective Route to the Ezoaminuroic Acid Core of the Ezomycins

Starting from readily available (R)-glycidol, an efficient pathway to a strategically functionalized ezoaminuroic acid derivative of the antifungal ezomycins has been developed. A key transformation in the synthesis involves regio- and stereoselective conversion of the olefinic functionality of a 5,6-dihydropyran-2-one to the C-2, C-3 trans-1,2-amino alcohol moiety as present in ezoaminuroic acid.

Total Synthesis of Cytotoxic Anhydrophytosphingosine Pachastrissamine (Jaspine B)

Starting from L-serine, a stereoselective synthesis of pachastrissamine, a structurally novel anhydrosphingosine derivative, is reported in this Letter. [structure: see text]