Spiropiperidines. I. Synthesis of 1'-substituted spiro[4H-3,1-benzoxazine-4,4'-piperidin]-2(1H)-one derivatives and evaluation of their antihypertensive activity

A cascade approach to 3D cyclic carbamates via an ionic decarboxylative functionalization of olefinic oxamic acids

An m-CPBA-mediated intramolecular epoxidation-decarboxylative alkoxylation cascade reaction of olefinic oxamic acids has been developed.

Synthesis and smooth muscle-selective relaxant activity of a piperidine analogue: 1-(4′-fluorophenacyl)-4-hydroxy-4-phenyl-piperidinium chloride

The antispasmodic and vasodilator activities of a newly synthesized piperidine derivative (1-(4'-fluorophenacyl)-4-hydroxy-4-phenyl-piperidinium chloride) were studied in vitro. The test compound exhibited a dose-dependent relaxant effect on the spontaneous and K+ (75 mM)-induced contractions of isolated rabbit jejunum with respective EC50 values of 0.01 mM (0.01-0.02, 95% Cl) and 0.30 mM (0.17-0.56). The Ca++ channel blocking (CCB) activity was confirmed when the test compound (0.1-0.2 mM) shifted the Ca++ dose-response curves to the right, similar to that produced by verapamil (0.1-1.0 microM), a standard CCB. In the isolated rabbit aorta, the test compound showed a dose-dependent vasodilator effect on K+ (75 mM)-induced contractions with an EC50 value of 0.08 mM (0.02-0.26) while also suppressed the norepinephrine (1 microM) control peak responses with EC50 value of 0.08 mM (0.05-0.13, n=5). When tested in Langendorff perfused rabbit heart preparation, the test compound exhibited a negligible inhibitory effect on the rate or force of atrial and ventricular contractions when tested up to 5 mM. The results show smooth muscle-selective relaxant effect of the test compound on intestinal and vascular preparations mediated possibly via blockade of voltage and receptor-operated Ca++ channels.

Diastereoselectivity in the reduction of alpha-Oxy- and alpha-amino-substituted acyclic ketones by polymethylhydrosiloxane

Diastereoselectivity in the reduction of alpha-alkoxy-, alpha-acyloxy-, and alpha-alkylamino-substituted ketones with polymethylhydrosiloxane (PMHS) in the presence of fluoride ion catalysis was investigated. High syn-selectivity was observed in the reduction of alpha-alkoxy, alpha-acyloxy, and alpha-dialkylamino ketones. Reduction of alpha-monoalkylamino ketone proceeded in anti-selective manner with moderate selectivity. The observed selectivity is explained based on Felkin-Anh and Cram-chelate models.

Studies on the effects of piperidine derivatives on blood pressure and smooth muscles contractions

Ten substituted phenacyl derivatives of 4-hydroxypiperidine were synthesized and studied for their effects on the mean arterial blood pressure (MABP) in normotensive anaesthetized rats and smooth muscles contractions of isolated rabbit jejunum. Two derivatives caused fall in blood pressure at the dose of 10-20 mg/kg and one rise in blood pressure at the dose of 20 mg/kg. Two compounds exhibited biphasic response (hypotensive followed by hypertensive) and one gave triphasic response at 10 mg/kg dose. Rest of four derivatives were found devoid of any effect on mean arterial blood pressure up to the dose of 30 mg/kg. All the derivatives except two caused relaxant effect on the spontaneous contraction of rabbit jejunum at the dose range of 0.1-2 mg/kg.