1.Synthesis and conformational analysis of 1,2-cis fused bicyclic α-d-galactofuranosyl thiocarbamate from per-O-tert-butyldimethylsilyl-β-d-galactofuranosyl isothiocyanate.
Baldoni L1, Stortz CA, Marino C. Carbohydr Res. 2011 Feb 1;346(2):191-6. doi: 10.1016/j.carres.2010.11.013. Epub 2010 Nov 19.
Per-O-tert-butyldimethylsilyl-α,β-d-galactofuranosyl isothiocyanate (4) was synthesized by the reaction of per-O-TBS-β-d-galactofuranose (1) with KSCN, promoted by TMSI. Upon O-desilylation (1,2-dideoxy-α-d-galactofuranoso)[1,2d]-1,3-oxazolidine-2-thione (6), the cis-fused bicyclic thiocarbamate was obtained as the only product. Conformational analysis, aided by molecular modelling, showed two stable twist forms ((3)T(4) and (4)T(O)) for the five-membered sugar ring in 6. In aqueous solution, the equilibrium favours the first conformation (3:1 ratio). On the other hand, this ratio decreases for less polar solvents.
2.(R)-2-Phen-oxy-1-(4-phenyl-2-sulfan-ylidene-1,3-oxazolidin-3-yl)ethanone.
Caracelli I, Coelho DC, Olivato PR, Correra TC, Rodrigues A, Tiekink ER. Acta Crystallogr Sect E Struct Rep Online. 2011 Oct 1;67(Pt 10):o2755-6. doi: 10.1107/S160053681103858X. Epub 2011 Sep 30.
The central 1,3-oxazolidine-2-thione ring in the title compound, C(17)H(15)NO(3)S, is approximately planar with maximum deviations of 0.036 (4) and -0.041 (5) Å for the O and methyl-ene-C atoms, respectively. The dihedral angles formed between this plane and the two benzene rings, which lie to the same side of the central plane, are 86.5 (2) [ring-bound benzene] and 50.6 (3)°. The ethan-1-one residue is also twisted out of the central plane, forming a O-C-N-C torsion angle of 151.5 (5)°. The dihedral angle formed by the benzene rings is 62.8 (2)° so that overall, the mol-ecule has a twisted U-shape. In the crystal, mol-ecules are linked into supra-molecular arrays two mol-ecules thick in the bc plane through C-H⋯O, C-H⋯S and C-H⋯π inter-actions.
3.Preparation and biological activity of four epiprogoitrin myrosinase-derived products.
Galletti S1, Bernardi R, Leoni O, Rollin P, Palmieri S. J Agric Food Chem. 2001 Jan;49(1):471-6.
(5R)-5-Vinyl-1,3-oxazolidine-2-thione, (2S)-1-cyano-2-hydroxy-3-butene, and two diastereoisomeric erythro-(2S)- and threo-(2S)-1-cyano-2-hydroxy-3,4-epithiobutanes were prepared in pure form starting from (2S)-2-hydroxybut-3-enyl glucosinolate (epiprogoitrin). This glucosinolate was isolated in almost pure form using ripe seeds of Crambe abyssinica and then hydrolyzed under different conditions. The hydrolysis was carried out using either myrosinase immobilized on nylon, to produce (5R)-5-vinyl-1,3-oxazolidine-2-thione, or the endogenous myrosinase contained in defatted crambe meals, to produce the other epiprogoitrin-derived products. After purification and physicochemical characterization, all four myrosinase degradation products were tested for their biological activity. A bioassay on Lactuca sativa was chosen as a simple test to determine their apparent action on living tissues. (5R)-5-Vinyl-1,3-oxazolidine-2-thione negatively affected mainly root growth, whereas (2S)-1-cyano-2-hydroxy-3-butene affected the early phase of germination, and both (2S)-1-cyano-2-hydroxy-3,4-epithiobutane diastereoisomers appeared to negatively affect both germination and root growth at doses 5-10 times lower than those of (2S)-1-cyano-2-hydroxy-3-butene or (5R)-5-vinyl-1,3-oxazolidine-2-thione.
