The 2:1 Adduct of an α-L-Altropyranose Derivative with Hexafluoro-2,6-dihydroxy-2,6-bis(trifluoromethyl)-4-heptanone at 173 K

As reported earlier [Miethchen, Rentsch & Michalik (1994). Liebigs Ann. Chem. pp. 219-222], the structure of methyl 2-O-(cyclohexylcarbamoyl)-6-deoxy-3,4-O-(hexafluoroisopropylidene)-α-L-altropyranoside, C 17 H 23 F 6 NO 6 could be determined by X-ray analysis of a species which was obtained by co-crystallization with 1,1,1,7,7,7-hexafluoro-2,6-dihydroxy-2,6-bis(trifluoromethyl)-4-heptanone, C 9 H 6 F 12 O 3 , in a 2:1 molar ratio. While the pure α-L-altropyranose derivative forms needles that are not suitable for single-crystal X-ray investigations, the co-crystallization product yielded well shaped monoclinic prisms. The L-altropyranose derivative adopts a ring conformation which is intermediate between a boat and a twisted-boat conformation. The structure is stabilized by four intermolecular hydrogen bonds