THE 2 1-ADDUCT OF AN ALPHA-L-ALTROPYRANOSE DERIVATIVE WITH 2,6-DIHYDROXY-2,6-BIS(TRIFLUOROMETHYL)-4-HEPTANONE AT 173K/

As reported earlier [Miethchen, Rentsch and Michalik (1994). Liebigs A nn. Chem. pp. 219-222], the structure of methyl hexafluoroisopropylide ne)-alpha-L-altropyranoside, C17H23F6NO6, could be determined by X-ray analysis of a species which was obtained by co-crystallization with , 6-dihydroxy-2,6-bis(trifluoromethyl)-4-heptanone, C9H6F12O3, in a 2:1 molar ratio. While the pure alpha-L-altropyranose derivative forms nee dles that are not suitable for single-crystal X-ray investigations, th e co-crystallization product yielded well shaped monoclinic prisms. Th e L-altropyranose derivative adopts a ring conformation which is inter mediate between a boat and a twisted-boat conformation. The structure is stabilized by four intermolecular hydrogen bonds.