Search

Synthesis of Annonaceous acetogenins, comprising asimicin and bullatacin, by naked carbon skeleton strategy, the convergent , and a hybrid approach is described. A library of 64 sterioisomers of the two compounds is constructed using all the above three approaches. Asimicin and bullatacin possess antitumor, antimalarial, immunosuppressive, and pesticidal properties.

The solid-phase protein synthesis protocol includes a highly stable, safety catch acid-labile linker that is compatible with a range of N-terminal protecting groups and ligation reactions. The linker produces an amide C-terminus after cleavage. The synthesis of vMIPI protein containing 3 peptides is illustrated.

Total synthesis of (+)-squamotacin, a substance which is known to have cytotoxic selectivity for human prostate tumor cells, is discussed. The starting material was (+)-muricatacin. The synthesis involved 27 steps and yield was at 0.83%. All asymmetric centers of the bistetrahydrofuran fragments were produced via asymmetric epoxidation (AE) reactions and Sharpless asymmetric dihydroxylation (AD).

A study was conducted to analyze the total synthesis of (+)-trilobin in 22 steps and 2.74% yield using the naked carbon skeleton scheme. 1H and 13C nuclear magnetic resonance spectra were determined in CDCl3 at 400 and 100 MHz, respectively. The synthesis was started with alcohol prepared by LAH reduction of the ethyl pentadec-4-enoate. Optical rotations were determined in a 1-dm cell. Column chromatographic separations were then carried out on silica gel.

Research was conducted to develop the first total synthesis of naturally occurring (+)-uvaricin. The methodology employed were three consecutive Sharpless asymmetric dihydroxylation reactions to incorporate the necessary stereochemical features in a regio- and enantioselectively controlled manner. A Williamson type etherification reaction was used on a functionalized bis-mesylate intermediate for the construction of the appropriate bis-THF ring system.

The 'naked carbon skeleton' approach was applied to the total synthesis of the 18-membered lichen macrolide (+)-aspicilin to demonstrate its advantages in the total synthesis of a number of natural products. The alternative strategy proceeds with the easy preparation of the nonfunctionalized carbon skeleton of the target molecule, hexadeca-1,3,15-triene. All the necessary stereogenic carbinol centers are then introduced onto the partially unsaturated hydrogen chain. Asymmetric total synthesis of (+)-aspicilin was achieved in 14 steps and 11% overall yield.

Sharpless asymmetric dihydroxylation reaction provides either (R) or (S) enantiomerically pure methylcarbinol groups from monosubstituted alkenes. Synthesis of the four stereoisomers of the western corn rootworm (WCR), Diabrotica virgifera virgifera, sex pheromone, involves six processes. Different methodologies are used to attain extremely facile formal total synthesis of antibiotic (-)-A26771B.

The fluorescent, heteroaromatic compound tricycloquinazoline (TCQ) forms the core fragment of a newly discovered class of discotic mesogens characterized by a C3 symmetry and 6 aliphatic side chains. Alkylation of hexahydroxy-TCQ, a product derived by trimerization of 5,6-dimethoxyanthranil succeeded by demethylation of the resulting hexamethoxy-TCQ, yields TCQ. TCQ, the discotic mesogen molecule, is characterized by a planner structure and a ring of 4 to 9 aliphatic side chains.

Enzymatic asymmetric reduction of polyfunctional ketones provides the enantiomerically pure alcohols for the total synthesis of the four isomers of 8-methyldec-2-yl propanoate, the sex pheromone of the western corn rootworm, Diabrotica virgifera virgifera LeConte. Thermoanaerobium brockii alcohol dehydrogenase catalyzes the reduction of nonane-2,8-dione to the chiral (2S,8S)-(+)-2,8-dihydroxynonane. The chiron individually yields in three to five steps the four enantiomers in practically 100% chiral purity.

A 14 step, asymmetric scheme yields (+)-aspicilin from the achiral hydrocarbon precursor, hexadecatriene. The reaction mechanism includes asymmetric hydroxylation (AD) reaction to obtain stereogenic carbinol centers by using both alpha-and beta-AD mixes. Aspicilin is an 18-membered lichen macrolide. The reaction is highly regio- and enantioselective.

Low-barrier molecular rotary motors having rotaxane architecture are constructed by using a cucurbituril host and a polyyne guest serving as stator and rotator. The repulsive interaction between there components is analyzed by using molecular mechanics calculations and is verified by X-ray crystallography with many synthetic host-guest complexes.

A synthetic route to 32 stereoisomers of a 10-carbon skeleton of bis-tetrahydrofuran (THT) acetogenins isolated from the Annonaceae family of plants was developed. The procedure, which was used to achieve the total synthesis of trilobacin for the first time, involves the generation and coupling of a phosphonium salt acting as a Wittig reagent and an aldehyde, oxidative cyclization with rhenium oxide and Mitsunobu inversion of alcohols.