SYNTHETIC STUDIES ON VIRANTMYCIN .1. TOTAL SYNTHESIS OF (+ -)-VIRANTMYCIN AND DETERMINATION OF ITS RELATIVE STEREOCHEMISTRY/

The efficient and stereospecific route to the tetrahydroquinoline ring models 3 and 4 of virantmycin has been developed by means of an intra molecular nitrene addition reaction as a key step. In the NOE experime nts of 4 and 3 we revealed that a ring inversion occurs in their piper idine ring system and determined the relative stereochemistry by captu ring each half-chair conformer as cyclic carbamates 26 and 27, respect ively. Utilizing this protocol total syntheses of (+/-)-1 and its dias tereomer (+/-)-2 have been accomplished and the relative stereochemist ry of virantmycin has been established as shorn in 1. Copyright (C) 19 96 Elsevier Science Ltd