Reactions of Sodium Salts of 3-(Hydroxymethylene)alkan-2-ones with Enamines: Synthesis of Polysubstituted Pyridines

Reactions of sodium salts of 3-(hydroxymethylene)alkan-2-ones with enamines afford 3-cyano-2-(disubstituted-methylene) -1,2-dihydropyridines.

A Novel and Efficient Method for the Synthesis of N-Arylsulfonylamino-2-pyridones

A novel and efficient method for the synthesis of N-arylsulfonylamino-2-pyridones, via the reaction of N-cyanoaceto-hydrazides with ethyl arylidenecyanoacetate derivatives, is investigated; N-sulfonated aminopyridines are also prepared from the reaction of N-amino-2-pyridones with arylsulfonyl chlorides.

Synthesis of 1-(beta-D-glycopyranosyl)-3-deazapyrimidines from 2-hydroxy and 2-mercaptopyridines

The synthesis of new 4- and 5-substituted-3-cyanopyridine nucleosides has been performed by reacting the silylated pyridines and penta-omicron-acetyl-alpha -D-glycopyranose in dichloroethane in the presence of SnCl4. The free nucleosides were tested for their potential activity against HIV and different types of tumor.

P-glycoprotein substrates and antagonists cluster into two distinct groups

To gather further insight into the interaction between P-glycoprotein (Pgp) and its substrates, 167 compounds were analyzed in multidrug resistant human colon carcinoma cells. These compounds were selected from the National Cancer Institute Drug Screen repository using computer-generated correlations with known Pgp substrates and antagonists. The compounds were prospectively defined as Pgp substrates if cytotoxicity was increased > or =4-fold by the addition of cyclosporin A (CsA) and as Pgp antagonists if inhibition of efflux increased rhodamine accumulation by 4-fold. Among the 84 agents that met either criterion, 35 met only the criterion for substrates, 42 met only the criterion for antagonists, and only seven met both criteria. Thus, compounds interacting with Pgp form two distinct groups: one comprising cytotoxic compounds that are transported and have poor or no antagonistic activity and a second comprising compounds with antagonistic activity and no evidence of significant transport. Vinblastine accumulation and kinetic studies performed on a subset of 18 compounds similarly differentiated substrates and antagonists, but inhibition of 3H-azidopine labeling and induction of ATPase activity did not. These data support an emerging concept of Pgp in which multiple regions instead of specific sites are involved in drug transport.