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Polymorphism exhibits different physicochemical properties, which can impact the bioavailability and bioactivity of solid drugs. This study focused on identifying the polymorphs of ginsenoside compound K (CK) and studying their different behaviors in pharmacokinetics (PK) and pharmacodynamics (PD). Four CK polymorphs (form I, II, III, and IV) from organic solvents were characterized by scanning electron microscope (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and powder X-ray diffraction (PXRD). A feasible LC-MS/MS method was exploited to determine the PK parameters. Form II displayed the most exposure, followed by form I, III, and IV. Notably, all forms showed sex dimorphism, and the bioavailability in the female group was about two-fold higher than in the male group. The PD properties were investigated in carrageenan-induced acute paw inflammation, and form II at 20 mg/kg showed significant inhibition of edema by 42.7%. This study clarified the polymorphic, PK, and PD characters of four crystal forms of CK, and the data suggested that form II had the best efficacy for drug development.

A new norsesquiterpene nephthediol (1) and a new sesquiterpene nephthetetraol (2) were isolated with guaianediol (3) from a soft coral of the genus Nephthea. Their structures were deduced on the basis of spectroscopic methods.

A six-step asymmetric total synthesis of (20S)-camptothecin (1) has been accomplished in 25% overall yield starting from the known pyridone 3. The key steps in this synthesis are the chemoselective Ni-catalyzed hydrogenation of 3-cyanopyridone 6 to 3-formylpyridone 7 in AcOH/pyridine/H2O and the Davis asymmetric hydroxylation of tricyclic lactone 4 utilizing a chiral N-sulfonyloxaziridine into (4′S)-tricyclic hydroxylactone 2.

The new tetracyclic diterpenoid confertdiate (1) and two new ceramides, (2) and (3), have been isolated from the soft coral Sinularia conferta, collected from Sanya Bay, Hainan Island, China. Their structures have been elucidated by spectroscopic analysis, and comparison of the 13C NMR data with those of the known diterpenoid isomandapamate confirmed the structure of 1.

An efficient and highly stereoselective total synthesis of d-biotin has been achieved starting from cis-1,3-dibenzyl-2-imidazolidone-4,5-dicarboxylic acid (2) with an overall yield of 33%. Polymer-supported oxazaborolidine-catalyzed asymmetric reduction of meso-cyclic imide 4 constitutes the key synthetic step in introducing stereogenic centers into the d-biotin molecule.

A novel and convenient method for the stereoselective synthesis of d-biotin 1 starting from the commercially available cis-1,3-dibenzyl-2-imidazolidone-4,5-dicarboxylic acid 2 has been developed. The key features of this synthesis include the enantioselective reduction of a meso-cyclic imide, mediated by a chiral oxazborolidine catalyst, derived from (1S,2S)-(+)-threo-1-(4-nitrophenyl)-2-amino-1,3-propanediol and the direct introduction of a C5 side chain to the (3aS,6aR)-thiolactone through a modified di-Grignard reaction. Enantioselectivities of 98% in the oxazborolidine-catalyzed asymmetric reduction process have been achieved.

An efficient and highly enantioselective synthesis of d-biotin from the known cis-1,3-dibenzyl-2-imidazolidone-4,5-dicarboxylic acid (5) was accomplished in 48% overall yield. The key reactions in the sequence involve thecatalytic enantioselective reduction of meso-cyclic imide 6 using polymer-supported chiral oxazoborolidine, derived from (S)-α,α-diphenylprolinol and polymer-bound sulfonyl chloride, and the installation of the C 5 side chain at C4 in the thiolactone 9 via a Ni/C-catalyzed Fukuyama coupling reaction.

(2004). A PRACTICAL PROCEDURE FOR THE SYNTHESIS OF 3-((E)-5-(2,3,4,5-TETRAMETHOXY-6-METHYLPHENYL)-3METHYLPENT-3-ENYL)-2,2-DIMETHYLOXIRANE. Organic Preparations and Procedures International: Vol. 36, No. 5, pp. 476-479.

In the title compound, C 10 H 14 BrNO 3 , the six-membered lactone ring is in a boat conformation, with the two carbonyl groups cis to one another across the boat basal plane. C-H...O hydrogen bonds and weak C-H...Br interactions stabilize the crystal structure.