LiCl-promoted amination of β-methoxy amides (γ-lactones).

An efficient and mild method has been developed for the amination of β-methoxy amides (γ-lactones) including natural products michelolide, costunolide and parthenolide derivatives by using lithium chloride in good yields. This reaction is applicable to a wide range of substrates with good functional group tolerance. Mechanism studies show that the reactions undergo a LiCl promoted MeOH elimination from the substrates to form the corresponding α,β-unsaturated intermediates followed by the Michael addition of amines.

A Series of Enthalpically Optimized Docetaxel Analogues Exhibiting Enhanced Antitumor Activity and Water Solubility.

A dual-purpose strategy aimed at enhancing the binding affinity for microtubules and improving the water solubility of docetaxel led to the design and synthesis of a series of C-2- and C-3'-modified analogues. Both aims were realized when the C-3' phenyl group present in docetaxel was replaced with a propargyl alcohol. The resulting compound, 3f, was able to overcome drug resistance in cultured P-gp-overexpressing tumor cells and showed greater activity than docetaxel against drug-resistant A2780/AD ovarian cancer xenografts in mice.

Bifunctional N-heterocyclic carbene catalyzed [3+4] annulation of enals and aurones.

Bifunctional N-heterocyclic carbenes with a free hydroxy group are demonstrated as efficient catalysts for the [3+4] annulation of enals with aurones to give the corresponding benzofuran-fused ε-lactones in good yields with good diastereoselectivities and excellent enantioselectivities. Control experiments reveal that the [3+4] cycloadducts are kinetically favored and could be transformed to the thermodynamically favored [3+2] cycloadducts with a non-bifunctional NHC catalyst.

Organocatalytic [4 + 2] cyclocondensation of α,β-unsaturated acyl chlorides with imines: highly enantioselective synthesis of dihydropyridinone and piperidine derivatives.

The cinchona alkaloid-catalyzed [4 + 2] cyclocondensation of α,β-unsaturated acyl chlorides with imines is developed to give the corresponding substituted dihydropyridinones in good yields with high to excellent enantioselectivities. Reduction of the dihydropyridinones gave highly optically active substituted tetrahydropyridinone and piperidine derivatives.

Catalytic [4+2] cyclization of α,β-unsaturated acyl chlorides with 3-alkylenyloxindoles: highly diastereo- and enantioselective synthesis of spirocarbocyclic oxindoles.

Cinchona alkaloids were used as Lewis base catalysts in the title reaction. The [4+2] cyclization of α,β-unsaturated acyl chlorides with electron-deficient alkenes derived from oxindole gave the corresponding spirocarbocyclic oxindoles.

Radical-scavenging activity and mechanism of resveratrol-oriented analogues: influence of the solvent, radical, and substitution.

Resveratrol (3,5,4'-trihydroxy-trans-stilbene, 3,5,4'-THS) is a well-known natural antioxidant and cancer chemopreventive agent that has attracted much interest in the past decade. To find a more active antioxidant and investigate the antioxidative mechanism with resveratrol as the lead compound, we synthesized 3,5-dihydroxy-trans-stilbene (3,5-DHS), 4-hydroxy-trans-stilbene (4-HS) 3,4-dihydroxy-trans-stilbene (3,4-DHS), 4,4'-dihydroxy-trans-stilbene (4,4'-DHS), 4-hydroxy-3-methoxy-trans-stilbene (3-MeO-4-HS), 4-hydroxy-4'-methoxy-trans-stilbene (4'-MeO-4-HS), 4-hydroxy-4'-methyl-trans-stilbene (4'-Me-4-HS), 4-hydroxy-4'-nitro-trans-stilbene (4'-NO(2)-4-HS), and 4-hydroxy-4'-trifluoromethyl-trans-stilbene (4'-CF(3)-4-HS). The radical-scavenging activity and detailed mechanism of resveratrol and its analogues (ArOHs) were investigated by the reaction kinetics with galvinoxyl (GO(*)) and 2,2-diphenyl-1-picrylhydrazyl (DPPH(*)) radicals in ethanol and ethyl acetate at 25 degrees C, using UV-vis spectroscopy.