Optically active sugar thioamides from d-gluconolactone Marõ  a J. AreÂvalo, Martõ  n Avalos, Reyes Babiano, AndreÂs Cabanillas, Pedro Cintas, Jose L. JimeÂnez* and Juan C. Palacios Departamento de QuõÂmica Orga Ânica, Facultad de Ciencias, Universidad de Extremadura, E-06071 Badajoz, Spain Received 17 March 2000; accepted 6 April 2000 Abstract This paper describes a facile and rapid approach to N-alkyl- and N-aryl-thiogluconamides employing d-gluconolactone as starting material. The protocol involves a three-step sequence to aord the corre- sponding thioamides as crystalline substances in moderate to good yields. The Lawesson reagent was found to be the reagent of choice to accomplish the key transformation amide±thioamide. # 2000 Elsevier Science Ltd. All rights reserved. 1. Introduction Carbohydrates represent the most ubiquitous source of chiral pool in nature and are therefore ideal precursors to access enantiomerically pure targets. Carbohydrate templates are available in a wide variety of chain lengths, cyclic and acyclic structures, and remarkably they are endowed with a plethora of stereochemical and conformational features which can be exploited in synthesis. 1 Moreover, methods for the transformation of sugar molecules into synthetically useful, yet chiral derivatives are likewise relevant. 1a,b Recently, we have developed several syntheses of sugar thioamides, 2,3 which serve as suitable precursors of optically active heterocycles 4 and of other functional groups. 5 7 Traditional methods have been based on the reaction of glycosyl cyanides with hydrogen sul®de, 8 and more recently, on the condensation of aldonodithioates with hetero- cyclic amines 9 and reactions of aminosugars with dithiocarboxylic esters or O-ethyl thioformate. 10 These protocols have been applied to cyclic sugars, especially glycopyranosyl or ribopyranosyl derivatives to nucleosides and their analogs. 0957-4166/00/$ - see front matter # 2000 Elsevier Science Ltd. All rights reserved. PII: S0957-4166(00)00140-3 Tetrahedron: Asymmetry 11 (2000) 1985±1995 * Corresponding author. E-mail: pecintas@unex.es