A general and efficient phosphorous acid-catalyzed cyclocondensation of β-ketoesters with o-aminobenzamides via selective C-C bond cleavage leading to quinazolinones is developed. This reaction proceeds smoothly under metal- and oxidant-free conditions, giving both 2-alkyl- and 2-aryl-substituted quinazolinones in excellent yields. This strategy can also be applied to the synthesis of other N-heterocycles, such as benzimidazoles and benzothiazoles.

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All solvents and reagents were used without purification. The reactions were monitored by GC. 1 H-NMR and 13 C-NMR spectra were recorded on a 400 MHz spectrometer (400 MHz for 1 H NMR, 100 MHz for 13 C NMR). CDCl 3 was used as the solvent. 1 H-NMR chemical shifts are reported using TMS as internal standard, 13 C-NMR chemical shifts are reported relative to CDCl 3 as internal standard. Flash column chromatography was performed over silica gel 30-60 μm. GC analysis was performed on GC-2014. Alkynes, aldehydes and ketones were purchased from Energy Chemical, Alfa-Aesar, Aladdin or Maya Reagent.

In order to improve the stability of direct current (DC) microgrid with constant power loads, a novel virtual inductive approach is proposed in this paper. It is known that the negative impedance characteristic of constant power loads will lead to DC bus voltage fluctuation, which will be more serious when they integrate into the DC microgrid though a large transmission line inductive. For the convenience of analysis, a simplified circuit model of the system is obtained by modeling the distributed resources. Unlike the existing control strategies, the proposed control strategy constructs a negative inductance link, which helps to counteract the negative effects of the line inductive between the power source and the transmission line. Detailed performance comparison of the proposed control and virtual capacitance are implemented through MATLAB/simulink simulation. Moreover, the improved performance of the proposed control method has been further validated with several detailed studies. The results demonstrate the feasibility and superiority of the proposed strategy.