(4R)-4-(2-Allyl-2H-1,2,3-triazol-4-yl)-1,2-O-isopropylidene-l-threose

X-ray crystallography unequivocally confirmed the structure of the title compound, C12H17N3O4, as (4R)-4-(2-allyl-2H-1,2,3-triazol-4-yl)-1,2-O-isopropylidene-l-threose. The absolute configuration was determined by the use of d-glucorono-3,6-lactone as the starting material. The crystal structure consists of hydrogen-bonded chains of molecules running parallel to the a axis. There are no unusual packing features.


Comment
The process for the biotechnological interconversion of monosaccharides developed by Izumori (Izumori, 2002;Izumori, 2006;Granstrom et al., 2004), has been seen to be generally applicable to other sugar derivatives such as 1-deoxy sugars Booth et al. 2008;Jenkinson, Booth, Gullapalli et al., 2008;Jenkinson, Booth, Yoshihara et al., 2008;Gullapalli et al., 2007). To evaluate the applicability of this process to 2-deoxy sugars and their derivatives a variety of carbon chain extension reactions were investigated, for example, addition of lithium tert-butyl acetate to sugar lactones (Jenkinson, Booth, Best et al., 2008) or addition of allyl magnesium bromide to an aldose.

Refinement
In the absence of significant anomalous scattering, Friedel pairs were merged and the absolute configuration was assigned from the starting material.
The relatively large ratio of minimum to maximum corrections applied in the multiscan process (1:1.22) reflect changes in the illuminated volume of the crystal. Changes in illuminated volume were kept to a minimum, and were taken into account (Görbitz, 1999) by the multi-scan inter-frame scaling (DENZO/SCALEPACK, Otwinowski & Minor, 1997).
The H atoms were all located in a difference map, but those attached to carbon atoms were repositioned geometrically.
The H atoms were initially refined with soft restraints on the bond lengths and angles to regularize their geometry (C-H in the range 0.93-0.98, O-H = 0.82 Å) and U iso (H) (in the range 1.2-1.5 times U eq of the parent atom), after which the positions were refined with riding constraints.