2008-07-3Relevant articles and documents
Aggregation induced emission (AIE) active β-ketoiminate boron complexes: Synthesis, photophysical and electrochemical properties
Kumbhar, Haribhau S.,Shankarling, Ganapati S.
, p. 85 - 93 (2015)
New keto-enol tautomeric benzoxazolyl and benzthiazolyl-1,2-diaryl β-ketoiminate based organoboron complexes have been synthesised and their fluorescence properties investigated. Boron complexes are widely known for their fluorescent properties, here we have synthesized organoboron complexes that show bright fluorescence in solid state and hardly any fluoresce in solution. These compounds exhibit aggregation induced emission (AIE) activity. Density functional theory (DFT) was employed for geometry optimisation and molecular orbital distribution computations in the ground state of the molecules. Electrochemical study demonstrates that these molecules possess high electron affinities as compared to the current electroluminescent materials like tris(8-hydroxyquinoli- nato)-aluminium (Alq3) and BODIPY, indicating the prospects of these boron complexes as an cient emitters in the optoelectronics.
Cu-catalyzed Asymmetric Dearomative [3 + 2] Cycloaddition Reaction of Benzazoles with Aminocyclopropanes
Zhang, Meng-Cheng,Wang, Dong-Chao,Xie, Ming-Sheng,Qu, Gui-Rong,Guo, Hai-Ming,You, Shu-Li
, p. 156 - 167 (2019)
The enantioselective dearomative [3 + 2] cycloaddition reaction of benzazoles with aminocyclopropanes has been successfully developed. In the presence of a copper complex, derived from Cu(OTf)2 and bisoxazoline, a series of hydropyrrolo-benzazole derivatives containing quaternary stereogenic centers were obtained in high yields with excellent enantioselectivity. This method could also provide 2-amino cyclopropanes with high enantiomeric purity by an efficient kinetic resolution. In addition, products could be transformed to pyrrolo-benzothiazines and 1,5-benzothiazepines. Chiral compounds are of great significance in many areas given that two corresponding enantiomers could have completely different properties in chiral environments. Therefore, technologies used to produce chiral compounds in their enantiopure form are particularly attractive and highly desirable. Catalytic asymmetric dearomatization reactions have become efficient methods for the construction of chiral fused- or spiro-heterocycles from simple aromatics. Polyheterocyclic structures containing a hydropyrrolo-azole motif are found extensively in natural products and biologically active compounds. Therefore, efficient methods for constructing complex chiral hydropyrrolo-azole compounds will benefit the lead identification in drug discovery. Herein, we report the highly enantioselective construction of hydropyrrolo-benzazoles via copper-catalyzed dearomative [3 + 2] cycloaddition of benzazoles with donor-acceptor aminocyclopropanes. Heterocycles are a very important class of compounds that exist extensively as structural cores in natural products and biologically active molecules. Catalytic asymmetric dearomatization (CADA) is an efficient strategy for the construction of chiral fused- or spiro-heterocycles from simple planar aromatic compounds. Herein, we report the development of enantioselective dearomative [3 + 2] cycloaddition reactions of benzazoles with aminocyclopropanes via kinetic resolution. In the presence of a copper complex, derived from Cu(OTf)2 and bisoxazoline, a series of hydropyrrolo-benzazole derivatives containing quaternary stereogenic centers were obtained in high yields (up to 99%) with excellent enantioselectivity (up to 99% enantiomeric excess [ee]). With the same catalytic system, 2-amino cyclopropane-1,1-dicarboxylates with a high enantiomeric purity (up to 98% ee) were also obtained by an efficient kinetic resolution (s values of up to 95). In addition, the utility of this method was showcased by the facile transformation of products into several important heterocyclic frameworks, including pyrrolo-benzothiazine and 1,5-benzothiazepine.
Break-and-Build Strategy for the Synthesis of 2-Benzoylbenzoxazoles from o-Aminophenols and Acetophenones
Nguyen, Le Anh,Ngo, Quoc Anh,Retailleau, Pascal,Nguyen, Thanh Binh
, p. 2098 - 2103 (2021/03/15)
Although compounds with a 2-benzoylbenzoxazole motif are biologically relevant, there are only a few methods for synthesizing them, most of which relied on multistep process or required substrates bearing activating groups. Herein, we report an efficient method for the synthesis of such compounds by direct reactions of o-aminophenols with acetophenones promoted by sulfur in DMSO. The reaction was found to proceed via a Willgerodt rearrangement-type benzoxazolation of acetophenones followed by a benzylic oxidation to reinstall the carbonyl function. This method has a broad substrate scope and good tolerance for sensitive functional groups. (Figure presented.).
