Chiral thioxohydroimidazoles with two sugar moieties. N-, C-, and spiro-nucleosides

2-Amino (alkyl and arylamino)-2-deoxy-D-fructose and different sugar isothi ocyanates are used in the diastereoselective synthesis of chiral imidazolid ine-2-thione hi-nucleosides 12-23. Water beta-elimination of these compound s produces imidazoline-2-thione N-nucleosides 27-31, whereas cyclodehydrati on of the same products gives, with high stereoselectivity, chiral spironuc leosides with an N-glycosyl radical 34-37. Conformational aspects of some o f the prepared compounds are discussed. (C) 2000 Elsevier Science Ltd. All rights reserved.