Isoprop­yl 2,5-anhydro-3,4-di-O-tert-butyl­diphenyl­sil­yl-L-ribonate

Determination of the crystal structure of the title compound, C₄₀H₅₀O₅Si₂, firmly established its relative configuration and hence that of some related tetra­hydro­furan carboxyl­ates. The material crystallizes with Z' = 2. Except for the chiral centres, the two independent mol­ecules are related by a pseudo-centre of symmetry.

1,2:3,4-Di-O-isopropyl­idene-α-D-tagatofuran­ose

The crystal structure of diacetone tagatose, C₁₂H₂₀O₆, establishes the stereochemistry of the anomeric spiro­acetal as 1,2:3,4-di-O-isopropyl­idene-α-D-tagatofuran­ose. Mol­ecules are linked by O—H...O hydrogen bonds [O...O = 2.862 (2) Å] to form chains running parallel to the b axis.

1,2:3,4-Di-O-isopropyl­idene-β-D-psicofuran­ose

The crystal structure of the title diacetone psicose, C₁₂H₂₀O₆, establishes the stereochemistry of the anomeric spiro­acetal 1,2:3,4-di-O-isopropyl­idene-β-D-psicofuran­ose. The structure consists of columns of mol­ecules linked by hydrogen bonds into chains [O...O 2.962 (2) Å] lying parallel to the a axis.