J. Wagner, P. Vogel
Dec 30, 1991
Citations
0
Influential Citations
4
Citations
Journal
Carbohydrate Research
Abstract
Abstract (1 R ,2 R ,4 R )-2- exo -Cyano-7-oxabicyclo[2.2.1]hept-5-en-2-yl (1 S )-camphanate [ 1 . Diels—Alder adduct of furan to 1-cyanovinyl (1 S )-camphanate, a “naked sugar”] was transformed with high stereoselectivity into (1 S ,4 S ,5 R ,6 R ,7 R )-6- exo ,7- exo -(isopropylidenedioxy)-4- exo -methyl-2,8-dioxabicyclo[3.2.1]octan-3-one [(−)- 4 ] and (1 S ,5 R ,6 R ,7 R )-6- exo ,7- exo -(isopropylidenedioxy)-4,4-dimethyl-2,8-dioxabicyclo[3.2.1] octan-3-one [(−)- 5 ]. Reaction of (−)- 5 with Me 3 SiCH 2 Li gave 5,7-dideoxy-5,5-dimethyl-2,3- O -isopropylidene- d - ribo - heptofuranos-6-ulose [(+)- 8 , which was then converted into 6-deoxy-5- C -methyl- d - ribo -hexose (10 steps from furan, 59% overall yield) and derivatives. N.m.r. studies established that branching of 6-deoxy- d -allose by a methyl group at C-5 favours the furanose versus the pyranose form of the carbohydrate in aqueous solution.