Stereoselective syntheses of the 2-Isopropenyl-2,3-dihydrobenzofuran nucleus: potential chiral building blocks for the syntheses of tremetone, hydroxytremetone, and rotenone.

The first enantioselective synthesis of the 2-isopropenyl-2,3-dihydrobenzofuran skeleton of tremetone and hydroxytremetone from (E)-4-(2-hydroxyphenyl)-2-methyl-2-butenyl methyl carbonate and (E)-4-(2,6-dihydroxyphenyl)-2-methyl-2-butenyl methyl carbonate, respectively, is described. The key step is a catalytic palladium-mediated reaction in the presence of the chiral Trost ligand.

Synthesis, natriuretic, antikaliuretic and antimagnesiuretic properties of an acidic triamterene derivative.

2,4,7-Triamino-6-(4-methanesulfonamidophenyl) pteridine (RPH 3048) is a new acidic triamterene derivative. Relevant physico-chemical constants were determined (solubility at pH 7.4 = 3.7 mg/l; logP at pH 7.4 = 0.2) and pharmacokinetic as well as pharmacodynamic properties were investigated, using male Wistar rats. After intravenous application of the test substances urine was collected, its volume and electrolyte composition determined, and the urine recovery of the drugs was analysed. The comparison of RPH 3048 with triamterene (CAS 396-01-0) revealed almost equipotent natriuretic and potassium-retaining effects for both drugs and an additional relative magnesium-sparing activity of RPH 3048. The urine recovery of RPH 3048 after 6 h was higher (20.6%) than that of triamterene (12.9%). No metabolite of RPH 3048 could be detected in the urine whereas a triamterene metabolite was found. Due to its good solubility in alkaline medium RPH 3048 could be dissolved (at pH 11-12) and then administered intravenously together with a loop diuretic (furosemide). Urinary electrolyte excretion following administration of two different combinations of RPH 3048 and furosemide (combination A: 12.5 mumol/kg RPH 3048 and 25 mumol/kg furosemide; combination B: 25 mumol/kg RPH 3048 and 25 mumol/kg furosemide) was compared to urinary electrolyte excretion of a control group and a group only treated with furosemide (25 mumol/kg). The additional application of RPH 3048 reduced in both groups potassium and magnesium excretion to control level but did not compromise furosemide induced natriuresis. In contrast to earlier investigations these results suggest that it is possible to develop acidic triamterene derivatives with potent antikaliuretic effects.