Insight into Pyridinium Chlorochromate Chemistry: Catalytic Oxidation of Tetrahydrofuran Compounds and Synthesis of Umbelactone

(±)-((2S,5R)-5-(Acetoxymethyl)tetrahydrofuran-2-yl)methyl Benzoate

In this note we report the synthesis of a doubly acylated cis-THF-diol product synthesised in three steps by the stereoselective RuO4-catalysed oxidative cyclisation of 1,5-hexadiene, followed by benzoylation and acetylation. This substance is one of the substrates chosen to probe a new developed oxidative procedure to transform bis-acylated THF-diols into bis-acylated 1,4-diketones. This new derivative was fully characterised by spectroscopic methods.

Sequential alcohol oxidation/putative homo Claisen–Tishchenko-type reaction to give esters: a key process in accessing novel biologically active lactone macrocycles

We report an efficient methodology for the direct oxidative esterification of primary alcohols to diether-esters using pyridinium chlorochromate (PCC).

(3R,3aR,6R,6aR)-Hexa-hydro-furo[3,2-b]furan-3,6-diyl dibenzoate

The title compound, C₂₀H₁₈O₆, prepared from d-mannitol by a two-step procedure, is a functionalized fused bis-tetra­hydro­furan. In the central fragment, consisting of two fused tetra­hydro­furan rings, one O atom and its two adjacent C atoms, a methyl­ene and a bridgehead C atom, are disordered over two sets of sites with an occupancy ratio of 0.735 (9):0.265 (9). In the major component, the ring containing the disordered O atom is a half-chair conformation with twisted methylene and benzoate-substituted C atoms, whereas the other ring has a half-chair or T-form conformation. In the minor component, the ring with the disordered O atom has an envelope conformation, with the O atom as the flap, and the other ring has a half-chair conformation, with the O atom and the other bridgehead CH atom being twisted. The two aromatic rings are inclined to one another by 20.00 (12)°. In the crystal, adjacent molecules are linked via C—H⋯π interactions, forming chains propagating along [010].

(3S,3aS,6R,6aR)-2-Oxohexa-hydro-furo[3,2-b]furan-3,6-diyl dibenzoate

The title compound, C₂₀H₁₆O₇, contains a cis-fused γ-lactone tetra­hydro­furan ring system functionalized with two benzo­yloxy groups. Both rings adopt an envelope conformation. The mol­ecule assumes an elongated shape and exibits non-crystallographic C₂ symmetry. The benzo­yloxy groups are almost planar [maximum deviations of 0.0491 (15) and 0.0336 (17) Å for the O atoms] and their mean planes are inclined to one another by 16.51 (4)°. The crystal packing features weak C—H⋯O inter­actions. The aryl groups of adjacent mol­ecules are parallel shifted with face-to-face contacts and a shortest inter­molecular C⋯C distance of 3.482 (4) Å.