Heterocyclization of 3-deoxy-D-erythro-hexos-2-ulose-1,2-bis(thiosemicarbazone). Crystal structure of the major diastereomer.
Both thiosemicarbazone groups of the derivative 1 of 3-deoxy-D-erythro-hexos-2-ulose underwent, on acetylation, a heterocyclization process to give (5R,5'R)-2,2'-diacetamido-4,4'-di-N-acetyl-5'-(1-deoxy-2,3,4-tri-O-acetyl-D-erythritol-1-yl)-5,5'-bis(1,3,4-thiadiazoline) (2) as a major product. The X-ray diffraction data of a single crystal of 2 indicated the R,R configuration for the stereocenters of the thiadiazoline rings (C-5 and C-5'). In the solid state, 2 adopts a sickle conformation (by clockwise rotation of the C-2-C-3 axis of the sugar chain) which has a S//O 1,3-parallel interaction. In solution, as determined by (1)H NMR spectroscopy which included NOE experiments, a similar sickle conformation was observed. From the reaction mixture of acetylation of 1 was isolated the bis(thiadiazoline) 3 as a by-product. The configuration of the C-5 and C-5' stereocenters of 3 were respectively assigned as S,R by comparison of the physical and spectroscopic data of this compound with those of 2.
CIHIDECAR (CONICET), Departamento de Química Orgánica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, 3o Piso, Pabellón II, Ciudad Universitaria, 1428 Buenos Aires, Argentina.
Miriam A
MA
Martins Alho
Ricardo
R
Baggio
María T
MT
Garland
Norma B
NB
D'Accorso
Oscar
O
Varela
D002236:Carbohydrate Conformation; D003460:Crystallization; D003500:Cyclization; D007661:Ketoses / Q000737:chemistry*; D008958:Models, Molecular; D013237:Stereoisomerism; D013882:Thiosemicarbazones / Q000737:chemistry*; D014961:X-Ray Diffraction
C474979:3-deoxy-D-erythro-hexos-2-ulose-1,2-bis(thiosemicarbazone); D007661:Ketoses; D013882:Thiosemicarbazones