The crystal and molecular structure of (4R,5R)-4-(1',2',3',4',5'-penta-O-ac
etyl-D-manno-pentitol-1-yl)-5-[N-(4-methoxyphenyl)carbamoyl]-2-(N-methylben
zylamino)-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}, C41H45N3
O14S, has been investigated at 150 K, The analysis of the crystal structure
allows the definition of the absolute configuration of the products of the
cycloaddition reaction between 3,5-di-phenyl-2-(N-methylbenzylamine)-1,3-t
hiazolium-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 dihydrothi
ophenes could be isolated. The configurations at the new C4 and C5 stereoce
ntres, with respect to that known at C6, are R,R. Except for a slight overa
ll contraction and a slightly altered geometry of the terminal acetyl group
, the structure is virtually the same as at room temperature.