This paper is dedicated to Prof. Raymond U . Lemieux on the occasion of his 60th birthday HANS H. BAERand ZAHER S. HANNA. Can. J. Chem. 59,889 (1981). Ethyl 4,6-di-0-acetyl-2,3-dideoxy-a-~-erythro-hex-2-enopyranoside (1) in the presence of triphenylphosphine and a catalytic amount of tetrakis(triphenylphosphine)palladium(O) reacted with a variety of amines or with reactive methylene compounds to give high yields of products aminated or C-alkylated, respectively, in an allylic position. Some analogous experiments were performed using the P-D-erythro anomer (2) and the a-D-threo epimer (3) of 1. The constitutions and configurations of the new products were established by means of mass spectra, 13C-and 'H-nmr spectra, and optical rotation data. The reactions of 1 were found to be highly regio-and stereoselective, giving almost exclusively Csubstituted 2-enopyranosides with retention of configuration, except in the case of dibenzylamine which produced a mlxture of the corresponding enoside and its 2-substituted, 3,Cunsaturated isomer having the a-D-threo configuration. The reactions of 2 appeared slightly less selective although they, too, furnished mainly 4-substituted 2-enopyranosldes with retention of configuration. Regioselectivity was low or lacking in two C-alkylations performed with 3, which gave mixtures of Csubstituted 2-enosides and 2-substituted 3-enosides. Some aspects of conformation and optical rotation in enopyranosides are discussed.HANS H. BAER et ZAHER S. HANNA. Can. J. Chem. 59,889 (1981).L
e compose C t h y l -4 , 6 -d i -O -a c e t y I -2 , 3 -d i d e s o x y -a -~n o p y r a n o s i d e
Introductioncally substituted product. The palladium species Recently we communicated (1) the first results of liberated upon collapse of the intermediary corna study concerning the potential utility of or-plex is reconverted into a catalytically active form ganopalladium reagents for the functionalization of by the action of the excess of triphenylphosphine carbohydrates. The present article reports full de-which is provided. A high degree of regioselectivity tails of the work and includes some additional re-and stereocontrol is normally observed in these sults which have since been elaborated. In connec-substitutions (6), although certain exceptions to tion with our current interest in the development of this welcome trend have been noted and discussed. methods for the synthesis of unusual amino, deoxy, As Our chief substrate for an the unsaturated, and branched-chain sugars (2), we de-utility of the method in the carbohydrate field,[ we cided to examine whether the palladium-catalyzed chose the crystalline ethyl 4,6-di-0-acetyl-2,3-disubstitution of allylic acetates by amines or reac-de0xy-cr-~-er~thro-hex-2-eno~~ranoside (I). his tive methylene compounds (3-6) might be em-compound is readily prepared (9) from commerplayed to advantage in carbohydrate chemistry. In c i a l l~ available D-glucal tfiacetate-For some anthis reaction, which represents one of the numer-cillary experiments, to be performed in the ...
