Compared to the aza-Wittig reaction of aldehydes, ketones, amides and esters, the aza-Wittig reaction of acid anhydride was always overlooked, which should be important part of Wittig reactions. Here, aza-Wittig reaction of anhydride and catalytic aza-Wittig reaction of anhydride were both developed with high yields, which provides an efficient method to synthesize of 4H-benzo[d][1,3]oxazin-4-ones and 4-benzylidene-2-aryloxazol-5(4H)-ones. The strategy of copper-catalyzed reduction of phosphine oxide was used and found effective for this transformation. Additionally, the one-pot catalytic aza-Wittig reaction of carboxylic acids was achieved. Furthermore, NMR experiments and Hammett plot recorded the process of catalytic aza-Wittig reaction of anhydride, which provides direct proof that the copper-catalyzed reduction of waste phosphine oxide is the key step in this transformation.
An efficient methodf or the synthesis of 1,2-dihydropyridine derivatives from simple andr eadily available aromatic ketones, DMF,a mines and propargylic alcohols has been developed via aB rønsted-acid-catalyzed multicompo-nent one-pot reaction. This reaction proceeded smoothly under metal-and ligand-free conditions in good yields, leading to functional organic molecules, via as elf-organized sequence.Scheme1.Single Brønsted-acid-catalyzed strategy.Scheme2.Biologicallyactive dihydropyridine and tetrahydropyridine derivatives.
Bisbenzothienyl iridium(III) complexes, [Ir(bt)2(PR3)]X (bt: 2-phenylbenzo[ d]thiazole, R = n-Bu or Ph, X = OTf, BF4 or SbF6) are reported, two of which, (R = n-Bu or Ph, X = OTf), have been characterised by X-ray crystallography. The complexes are thermally stable and their photophysical properties are presented, together with their catalytic activity in the “borrowing hydrogen reaction” of alcohols with amines.
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