Enantioselective Synthesis, DFT Calculations and Preliminary Antineoplastic Activity of Dibenzo 1-Azaspiro[4.5]decanes o...
Published in The Journal of Organic Chemistry
Determining Substrate Specificities of β1,4-Endogalactanases Using Plant Arabinogalactan Oligosaccharides Synthesized by...
Published in The Journal of Organic Chemistry
Automated Glycan Assembly of Complex Oligosaccharides Related to Blood Group Determinants
Published in The Journal of Organic Chemistry
Pro-Apoptotic and Immunostimulatory Tetrahydroxanthone Dimers from the Endophytic Fungus Phomopsis longicolla
...Published in The Journal of Organic Chemistry
Four tetrahydroxanthone dimers (1-4) and four biogenetically related monomers (5-8), including the new derivatives (4-6), were isolated from the endophyte Phomopsis longicolla. The absolute configurations of 2-4 were established for the first time by TDDFT ECD calculations and that of phomoxanthone A (1) was revised by X-ray crystallography. Phomox...
Intramolecular general base catalysis in the hydrolysis of a phosphate diester. Calculational guidance to a choice of me...
Published in The Journal of Organic Chemistry
Notwithstanding its half-life of 70 years at 25 °C, the spontaneous hydrolysis of the anion of di-2-pyridyl phosphate (DPP) is thousands of times faster (ca. 3000 at 100 °C, over 10000-fold at 25 °C) than expected for a diester with leaving groups of pK(a) 9.09. The kinetic parameters do not permit a conclusive choice between five possible mechanis...
The base-catalyzed keto-enol interconversion of 2-nitrocyclohexanone in ionic liquids.
Published in The Journal of Organic Chemistry
While the solvent effect on the rate of tautomerization of 2-nitrocyclohexanone in several organic solvents appears to depend essentially on the permittivity of the solvent, a different behavior is observed in some ionic liquids. In particular the rate of the reaction in ionic liquids (ILs) is much faster than expected solely on the basis of the pe...
Asymmetric synthesis of anti-aldol segments via a nonaldol route: synthetic applications to statines and (-)-tetrahydrol...
Published in The Journal of Organic Chemistry
An asymmetric synthesis of anti-aldol segments via a nonaldol route is described. The strategy involves a highly diastereoselective synthesis of functionalized tetrahydrofuran derivatives from optically active 4-phenylbutyrolactone. Treatment of the tetrahydrofuran derivatives with a Lewis acid and acetic anhydride provided the corresponding ring-o...
Synthesis and evaluation of the cytotoxicity of apoptolidinones A and D.
Published in The Journal of organic chemistry
Apoptolidins A-D are microbial secondary metabolites shown to be selectively cytotoxic against several cancer cell lines and noncytotoxic against normal cells. Total syntheses of apoptolidinones A and D are reported. The efficient synthetic strategy leading to the apoptolidinones features construction of the common 20-membered macrolactone by an in...
The [12]annulene global minimum.
Published in The Journal of Organic Chemistry
A new global minimum for [12]annulene has been computationally located. This mono-trans minimum 5 (CCCCCT) is computed to be 1.5 kcal/mol more stable (CCSD(T)/cc-pVDZ//BHHLYP/6-311+G**) than the known tri-trans isomer 1 (CTCTCT) and 2.4 kcal/mol lower than the di-trans isomer 4 (CCTCCT), for which there is indirect evidence. The barriers for severa...
Atropisomerism in the 2-arylimino-N-(2-hydroxyphenyl)thiazoline series: influence of hydrogen bonding on the racemizatio...
Published in The Journal of Organic Chemistry
A series of original atropisomeric iminothiazolines 1 in which X = OH or (and) Y = OH were prepared from the corresponding methoxy precursors. The resolution of the atropisomeric enantiomers on chiral support is reported, and the barriers to enantiomerization are given. These barriers were determined either by off-line racemization studies or by tr...
