Enantioselective synthesis of antibiotic (+)-rancinamycin III derivative and two protected carbasugars of the alpha-D-talo-series from furan

The synthesis of (+)-1, a carbasugar related to rancinamycin III, has been achieved from diene (+)-3 in two steps using as the key step the transforma tion of alkyne (-)-2, obtained by resolution of alcohol 6, into diene (+)-3 by treatment with Na/MeOH. Moreover, reduction of the carbonyl group in ()-1 affords diol (+)-19, in which different protection strategies of the hy droxy groups allows one to obtain, selectively, protected derivatives of al pha-D-carbatalopyranose (+)-4a and its 6-desoxy derivative (+)-4b to be obt ained selectively. (C) 1999 Elsevier Science Ltd. All rights reserved.