Chromatographic resolution of antihypertensive benzopyrans by closed-loop recycling enantioselective high pressure preparative chromatography and their X-ray analysis

The resolution of (+)-trans-3,4-dihydro-2,2-dimethyl-4-(2-oxopiperidin-1-yl )-2H-pyrano[3,2-c]pyridin-3-ol 1,(1) a potassium channel opener, has been a chieved using closed-loop recycling enantioselective preparative chromatogr aphy. The resolved enantiomers showed an ee of >97% based on analytical HPL C and H-1 NMR. The absolute configuration has been determined by X-ray anal ysis of the (R)-(+)-alpha-methylphenylcarbamoyl derivative of one of the en antiomers. (C) 1998 Elsevier Science Ltd. All rights reserved.