Study of a diastereoisomeric dihydrothiophene derivative at 150K

Abstract

The crystal and molecular structure of (4R, 5R)-4-(1', 2', 3', 4', 5'-penta-O-acetyl-D-manno-pentitol-1-yl)-5-[N-(4-methoxyphenyl)carbamoyl]-2-(N-methyl-benzylamino)-3-nitro-5-phenyl-4,5-dihydrothiophene {IUPAC name: 1-(2R,3R)-5-(N-benzyl-N-methylamino)-2-[N-(4-methoxyphenyl)carbamoyl]-4-nitro-2-phenyl-2,3-dihydro-3-thienyl]-1,2,3,4,5-penta-O-acetyl-D-manno-pentitol}, C 41 H 45 N 3 O 14 S, has been investigated at 150K. The analysis of the crystal structure allows the definition of the absolute configuration of the products of the cycloaddition reaction between 3,5-diphenyl-2-(N-methylbenzylamine)-1,3-thiazolium-7-olate and (E)-3,4,5,6,7-penta-O-acetyl-1,2-dideoxy-1-C-nitro-D-manno-hept-1-enitol, where only one of the two diastereoisomeric dihydrothiophenes could be isolated. The configurations at the new C4 and C5 stereocentres, with respect to that known at C6, are R,R. Except for a slight overall contraction and a slightly altered geometry of the terminal acetyl group, the structure is virtually the same as at room temperature.