Iridium(III)-Catalyzed Tandem Annulation of Pyridine-Substituted Anilines and α-Cl Ketones for Obtaining 2-Arylindoles.

A facile and expeditious protocol for the synthesis of 2-arylindole compounds from readily available N-(2-pyridyl)anilines and commercially available α-Cl ketones through iridium-catalyzed C-H activation and cyclization is reported here. As a complementary approach to the conventional strategies for indole synthesis, the transformation exhibits powerful reactivity, tolerates a large number of functional groups, and proceeds with good to excellent yields under mild conditions, providing a straightforward method to obtain structurally diverse and valuable indole scaffolds. Furthermore, the reaction could be easily scaled up to gram scale.

Rhodium-catalyzed tandem acylmethylation/annulation of N-nitrosoanilines with sulfoxonium ylides for the synthesis of substituted indazole N-oxides.

An atom-economical protocol for synthesizing indazole N-oxides from readily available N-nitrosoanilines and sulfoxonium ylides through the rhodium(iii)-catalyzed C-H activation and cyclization reaction is described here. This protocol employs nitroso as a traceless directing group. The transformation features powerful reactivity, tolerates various functional groups, and proceeds with moderate to good yields under an ambient atmosphere, providing a straightforward approach to access structurally diverse and valuable indazole N-oxide derivatives. Importantly, this new annulation process represents a hitherto unobserved reactivity pattern for the N-nitroso group.

Base-promoted Lewis acid catalyzed synthesis of quinazoline derivatives.

A one-pot protocol has been developed for the synthesis of quinazolinones from amide-oxazolines with TsCl via a cyclic 1,3-azaoxonium intermediate and 6π electron cyclization in the presence of a Lewis acid and base. The process is operationally simple and has a broad substrate scope. This method provides a unique strategy for the construction of quinazolinones.

Direct synthesis of 2,3,5-trisubstituted pyrroles via copper-mediated one-pot multicomponent reaction.

We have developed a copper-mediated one-pot synthesis of 2,3,5-trisubstituted pyrroles from 1,3-dicarbonyl compounds and acrylates using ammonium acetate as a nitrogen source. The reaction achieves C-C and C-N bond formation and provides an efficient approach to access highly functionalized pyrroles without further raw material preparation. This method is operationally simple, compatible with a wide range of functional groups, and provides the target products in moderate to good yields.

Ruthenium-catalyzed synthesis of indole derivatives from N-aryl-2-aminopyridines and alpha-carbonyl sulfoxonium ylides.

Indole is a ubiquitous structural motif with important applications in many areas of chemistry. Given this, a simple and efficient Ru(ii)-catalyzed synthesis of indole via intermolecular annulation of N-aryl-2-aminopyridines and sulfoxonium ylides was proposed and accomplished. Excellent selectivity and good functional group tolerance of this transformation were observed. This protocol provides easy access to a wide variety of useful indoles in the presence of a commercially available [Ru(p-cymene)Cl2]2 catalyst. A possible mechanism for the reaction pathway was also proposed. More importantly, this reaction will offer a useful method for the construction of enantioenriched indole frameworks.

Oxidative Recyclization of 1H-Indoles for Synthesis of 2-Indolylbenzoxazinones via Cleavage of the C2-C3 Bond with AIBN under Air.

A novel and concise method for the oxidation of unprotected indole derivatives to synthesize 2-indolylbenzoxazinones in the presence of AIBN under open air has been successfully demonstrated. This metal-free reaction is both atom- and step-efficient and is applicable to a broad scope of substrates. This new methodology provides a facile pathway for oxidative C2-C3 bond cleavage and recyclization of 1H-indoles.

Cu(I)-catalyzed synthesis of imidazo[1,2-a]pyridines from aminopyridines and nitroolefins using air as the oxidant.

A copper-catalyzed method for the synthesis of imidazo[1,2-a]pyridines with aminopyridines and nitroolefins using air as oxidation agent in a one-pot procedure has been developed. In this process, the reaction appears to be very general and suitable for construction of a variety of imidazo[1,2-a]pyridines.

Pd(II)-catalyzed synthesis of benzisoxazolones from benzohydroxamic acids via C-H activation.

A Pd-catalyzed method for the synthesis of benzisoxazolones from benzohydroxamic acids using Oxone as an oxidant in a one-pot procedure has been developed. In this process, the reaction appears to be suitable for construction of various benzisoxazolones.

Synthesis of oxazolidinones through ring-opening and annulation of vinylene carbonate with 2-pyrrolyl/indolylanilines under Rh(III) catalysis.

Herein, we have developed a rhodium-catalyzed C-H functionalization and subsequent intramolecular ring-opening/cyclization of vinylene carbonate with 2-pyrrolyl/indolylanilines, which leads to oxazolidinones in moderate to good yields. In this transformation, vinylene carbonate only eliminates one oxygen atom rather than -CO3 or CO2. Furthermore, some control experiments are conducted to elucidate the reaction mechanism.

Cu (I)-catalyzed synthesis of polysubstituted pyrroles from dialkyl ethylenedicarboxylates and beta-enamino ketones or esters in the presence of O2.

A straightforward method for the synthesis of polysubstituted pyrroles was achieved easily from oxidative cyclization of beta-enamino ketones or esters and alkynoates catalyzed by CuI in the presence of O(2).

[Compatible biomass models of natural spruce (Picea asperata)]. / 天然云杉相容性生物量估算模型.

By using nonlinear measurement error method, the compatible tree volume and above ground biomass equations were established based on the volume and biomass data of 150 sampling trees of natural spruce (Picea asperata). Two approaches, controlling directly under total aboveground biomass and controlling jointly from level to level, were used to design the compatible system for the total aboveground biomass and the biomass of four components (stem, bark, branch and foliage), and the total ground biomass could be estimated independently or estimated simultaneously in the system. The results showed that the R2 of the one variable and bivariate compatible tree volume and aboveground biomass equations were all above 0.85, and the maximum value reached 0.99. The prediction effect of the volume equations could be improved significantly when tree height was included as predictor, while it was not significant in biomass estimation. For the compatible biomass systems, the one variable model based on controlling jointly from level to level was better than the model using controlling directly under total above ground biomass, but the bivariate models of the two methods were similar. Comparing the imitative effects of the one variable and bivariate compatible biomass models, the results showed that the increase of explainable variables could significantly improve the fitness of branch and foliage biomass, but had little effect on other components. Besides, there was almost no difference between the two methods of estimation based on the comparison.

High triplet energy polymer as host for electrophosphorescence with high efficiency.

We report the conjugated polymer P(tBu-CBP) as a host with high triplet energy (E(T) 2.53 eV) and suitable HOMO (5.3 eV) and LUMO (2.04 eV) energy levels. Upon doping with green and red emission Ir-complexes, it gives devices with high luminous and external quantum efficiencies for green emission (23.7 cd/A, 6.57%) and for red emission (5.1 cd/A, 4.23%), respectively, and low turn-on voltage (3 V). For both devices, the efficiencies are higher than those of the corresponding devices with the same backbone P(3,6-Cz) as a host by a factor of 4, even though the latter has an E(T) (2.6 eV) slightly higher than that of the former. The results reflect that, in phosphorescent devices, the difference in E(T) between the host and guest is not the only factor that determines the device efficiency, and the present side group modification via the 9 position of carbazole also plays an important role, which allows a tuning of HOMO and LUMO levels to provide more balance in electron and hole fluxes and provides prevention from formation of excimer.