Search

A small molecule was under investigation as an inhibitor of glucosylceramide synthase (GCS) for potential use in Fabry disease. To support preclinical activities, a four-step synthesis was developed and used to prepared kilogram quantities of the drug substance. The new route features a scalable CDI-mediated Lossen rearrangement as a substitution for hazardous azide chemistry that was employed in the original route.

A series of new taxoids derived from 14 beta-hydroxy-10-deacetylbaccatin III was synthesized by means of the beta-lactam synthon method. Most of the new taxoids thus synthesized possess excellent cytotoxicity against human ovarian (A121), non-small-cell lung (A549), colon (HT-29), and breast (MCF-7) cancer cell lines, and several of these taxoids show subnanomolar IC50 values which are severalfold to 1 order of magnitude better than those of paclitaxel and docetaxel. Modifications at the 3'- and 3'-N-positions exert marked effects on the activity. For the substituents at C-3', the cytotoxicity decreases in the order 2-furyl approximately 2-methyl-1-propenylor = 2-methylpropyl(E)-1-propenylor = n-propylphenyl2,2-dimethylpropyl. For the 3'-N substituents, the activity decreases in the order t-BuOCOPhn-hexanoyl. A significant increase in the cytotoxicity against the doxorubicin-resistant human breast cancer cell line MCF7-R that expresses the multidrug resistance (MDR) phenotype is observed by the proper modification of the substituent at C-10. The observed remarkable effects of the substituents at C-10 on the activity against MCF7-R can be ascribed to the effective inhibition of the binding of these new taxoids to P-glycoprotein that is responsible for MDR.

A series of new fluorine-containing analogs of paclitaxel and docetaxel are synthesized using the coupling of (3R,4S)-1-acyl-β-lactams with high enantiomeric purity with properly protected baccatin III, 10-deacetylbaccatin III, and 14β-hydroxy-10-deacetylbaccatin III as the key step (β-Lactam Synthon Method). (3R,4S)-1-Acyl-β-lactams are prepared through efficient chiral ester enolate - imine cyclocondensation.

A series of substituted pyrazinoic acid esters has been prepared and examined for their in vitro activity against Mycobacterium avium and Mycobacterium kansasii as well as Mycobacterium tuberculosis. Modification of both the pyrazine nucleus and the ester functionality have been very successful in expanding the activity of pyrazinamide to include M. avium and M. kansasii, organisms normally not susceptible to pyrazinamide. Several of these compounds have activities 100-1000-fold greater than that of pyrazinamide against M. tuberculosis.

Fluoroolefin dipeptide isosteres were synthesized applying the Peterson reaction as a novel method for fluoroolefination. The dipeptide isosteres were elaborated to provide the conformationally constrained analogs ( 1 -( R ), 1 -( S ) and 2 -( R ), 2 -( S )) of the Suc-Ala-Gly-Pro-Phe-pNA tetrapeptide, a synthetic substate of cyclophilin.

Optically active monofluorinated amides were prepared via the amide acetal Claisen rearrangement and the establishment of the absolute stereochemistry of the rearranged products proved that the chiral auxiliary directed the approach of the crotyl fragment to the Si face of the ( E )- N,O -ketene acetal. The general utility of this type of rearrangement is also discussed.

A series of substituted pyrazinoic acid esters has been prepared and examined for their in vitro activity against Mycobacterium avium and Mycobacterium kansasii as well as Mycobacterium tuberculosis. Modification of both the pyrazine nucleus and the ester functionality have been very successful in expanding the activity of pyrazinamide to include M. avium and M. kansasii, organisms normally not susceptible to pyrazinamide. Several of these compounds have activities 100-1000-fold greater than that of pyrazinamide against M. tuberculosis.

A series of pyrazinoic acid esters has been prepared and evaluated for in vitro antimycobacterial activity. Several of the pyrazinoate esters have substantially better activity than the first-line antituberculous agent pyrazinamide against susceptible isolates of Mycobacterium turberculosis as well as activity against pyrazinamide-resistant isolates. The minimal inhibitory concentrations (MICs) were lower for each organism and at each pH than the MICs for pyrazinamide. The esters have activity against Mycobacterium bovis and Mycobacterium kansasii, two species resistant to pyrazinamide, but not against Mycobacterium avium complex.

Optically active monofluorinated amides were prepared via the amide acetal Claisen rearrangement and the establishment of the absolute stereochemistry of the rearranged products proved that the chiral auxiliary directed the approach of the crotyl fragment to the Si face of the ( E )- N,O -ketene acetal. The general utility of this type of rearrangement is also discussed.