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Although the NHC-catalyzed cyclization reactions have been well established for the synthesis of various heterocycles, the corresponding all carbon cyclization reaction for the synthesis of carbocycles is far less established. In this note, the NHC-catalyzed all carbon [4+2] cyclocondensation of α,β-unsaturated acyl chlorides and 3-alkenyloxindoles was developed to give the corresponding spirocarbocyclic oxindoles in good yield with good to high diastereoselectivities.

The single-side salt-freeze test was used to optimize the concrete mix design for improving the resistance of concrete to salt scaling. The results show that the resistance of concrete to salt scaling improves with decreasing water-cement ratio and increasing air content. Addition of silica fume also improves the resistance of concrete to salt scaling relative to fly ash, ground granulated blast-furnace slag, and other silica fume. To enhance the resistance to salt scaling of concrete pavements, the water- cement ratio should be less than 0.4, the air content higher than 3.8%, and the cementitious materials-aggregate ratio is 265∶745 to 280∶720. If fly ash and ground-granulated blast-furnace slag are used then extended curing is required to prevent salt scaling in early-age concrete. Finally, organic instead of inorganic snow-melting agents should be preferred.

The enantioselective N-heterocyclic carbene-catalyzed formal [2 + 2] and [2 + 2 + 2] cycloaddition of ketenes and isothiocyanates were developed. Reaction with N-aryl isothiocyanates at room temperature favors the [2 + 2] cycloaddition, while reaction with N-benzoyl isothiocyanates at -40 °C favors the [2 + 2 + 2] cycloaddition.

A straightforward synthesis of optically active trifluoromethyl dihydropyranones and spirocyclic oxindole-dihydropyranones has been realized by the chiral N-heterocyclic carbenes-catalyzed cyclization of α,β-unsaturated β-methylacyl chlorides with activated trifluoromethyl ketones or isatin derivatives.

The methanol extract of Ficus sarmentosa var. henryi (King) Corner was found to detect potent inhibitory activities against 6 crop pathogenic fungi, Fusarium graminearum, Pumpkin fusarium Wilt, Curvularia lunata (Wakker) Boed, Septoria zeicola Stout, Botrytis cinerea, and Rhizoctonia solani. Four flavonoids were isolated from the extract of F. sarmentosa var. henryi by activity-guided fractionation and they were identified as eriodictyol (1), homoeriodictyol (2), dihydroquercetin (3), and luteolin (4) by spectroscopic means and displayed excellent inhibitory activity against F. graminearum and S. zeicola. Among them, luteolin (4) showed the strongest inhibitory activity with IC50 values of 56.38 and 81.48 mg L−1, to the fungi, respectively. The in vitro inhibitory activity of F. sarmentosa var. henryi (King) Corner was reported for the first time and the inhibitory action mechanism of luteolin (4) was worthy of further research.

furnishing spirocarbocyclic oxindoles (III) (20 examples) with good to high stereoselectivity

This method yields the title compounds with high diastereoselectivities and good enantioselectivities (up to 93% e.e.).

Optically active terminal 1,2-diols were prepared with high enantiopurity via the TMS-quinidine-catalyzed enantioselective cyclization of acyl chlorides and oxaziridine, followed by reductive ring-opening of the cycloadducts.

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.

The [2 + 2]-cycloaddition reaction of the aromatic isothiocyanate (III) with ketenes proceeds at room temperature with formation of 4-thioxo-2-azetidinones.

The title quinidine-catalyzed reaction of cyclic or acyclic acyl chlorides affords dihydropyridazinones with high enantioselectivities, which can be converted into γ-amino amides or acids by reductive ring opening without loss of enantioselectivity.

A series of spirocyclic lactones (III) is prepared with good diastereo- and enantioselectivities by reaction of isatins (I) with enals (II) in the presence of a chiral N-heterocyclic carbene.

A straightforward synthesis of optically active trifluoromethyl dihydropyranones and spirocyclic oxindole-dihydropyranones has been realized by the chiral N-heterocyclic carbenes-catalyzed cyclization of α,β-unsaturated β-methylacyl chlorides with activated trifluoromethyl ketones or isatin derivatives.

A mechanism in which the catalytic reaction is initiated by addition of the N-heterocyclic carbene to ketenes rather than to carbon disulfide is proposed.

The cinchona alkaloid-catalyzed γ-amination of α,β-unsaturated acyl chlorides with azodicarboxylates to give the corresponding dihydropyridazinones in good yields with high enantioselectivities has been developed. Reductive ring opening of the dihydropyridazinones afforded series of cyclic and acyclic γ-amino acid derivatives in good yields with high enantiopurity.

The chiral N-heterocyclic carbene-catalyzed [2+2+2] cycloaddition of ketenes and carbon disulfide was realized to give the cycloadduct of 1,3-oxathian-6-ones in good yields with excellent enantioselectivities.

Distributed collaboration systems intend to provide software engineers as well as end-users the facilities to easily control and process their collaborative activities. This paper investigates our Scrutiny/CB architecture and environment through real usages and extensive simulation experiments. The analysis and evaluation results from this study provide insight observations and helpful guidance to the future improvement of distributed collaboration systems. >

The chiral N-heterocyclic carbene bearing a proximal hydroxy group derived from L-pyroglutamic acid was found to be an efficient catalyst for the [3+2] annulation of enals and isatins to give the corresponding spirocyclic oxindolo-γ-butyrolactones in good yield with good diastereo- and enantioselectivities.