RESUMEN
Besides chromatographic methods and biocatalyzed reactions, another alternative method of obtaining enantiomeric forms of beta-blockers is stereoselective synthesis. This paper links up with two preceding surveys concerning beta-blockers--groups of chiral agents and presents a survey of the hitherto published enantioselective syntheses of (R)- and (S)-enantiomers of beta-blockers. In the group of arylaminoethanols, mainly selective reduction of prochiral ketones in the presence of metallic complexes is used in this type of synthesis. Enantiomerically pure beta-blockers of the aryloxyaminopropanol type are synthesized by means of a reaction of pertinent phenols with different chiral precursors, such as (R) and (S)-chloromethyloxirans, (S)-glycidoltosylate, (S)- or (R)-2,3-O-isopropylideneglyceroltosylate, E-(2S,3S)-3-trimethylsilylglycidol and (S)-3-terc-butyl-5-phenyl-oxazolidine-5-ylmethanol. Many of these chiral semiproducts can be prepared from natural substances, such as D-mannitol and L-ascorbic acid.
Asunto(s)
Antagonistas Adrenérgicos beta/química , Antagonistas Adrenérgicos beta/síntesis química , EstereoisomerismoRESUMEN
An evaluation of anti-ulcer effects of mono- and dibasic carbamate local anaesthetics was performed using two experimental models of gastric ulcers, i.e. those induced by stress, or by ligation of the pylorus. These models have been found not to be identical. In the case of stress-induced ulcers, no experimental animal died as compared to the second experimental group with a 30% mortality rate due to the more frequent occurrence of ulcer perforations. Result similarities of both models could only be found with respect to the range of damage of the mucous membrane of the stomach. A premedication with a majority of basic carbamates decreased the incidence and range of ulcer lesion. The anti-ulcer activity of monobasic carbamates was more significant when compared with dibasic compounds.