N-Benzyl-3,5-dideoxy-3,5-imino-1,2-O-isopropylidene-β-l-lyxofuranose

X-ray crystallography confirmed the formation, structure and relative stereochemistry of the title compound, C15H19NO3, which contains a sterically congested four-membered azetidine ring system. The absolute configuration was determined by the use of l-arabinose as the starting material.

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: LH5500).
Azetidine formation can be achieved by the double displacement of ditriflates with amines Lenagh-Snow et al., 2011;Lenagh-Snow et al., 2012). X-Ray crystallography confirmed the structure and relative stereochemistry of the formation of the title compound 3 (Fig. 1) from the displacement of a 3,5-O-ditriflate 2 with benzylamine. The absolute stereochemistry was determined by the use of L-arabinose as the starting material.
The five membered rings adopt envelope conformations with O7 and C10 out of the plane, and the azetidine ring adopts a puckered conformation (Fig. 2, Fig. 3).

Refinement
In the absence of significant anomalous scattering, Friedel pairs were merged and the absolute configuration was assigned from the starting material.
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 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 (Cooper et al., 2010).