Bifunctional Organocatalysts for the Enantioselective Synthesis of Axially Chiral Isoquinoline N-Oxides
摘要:
Bifunctional catalysts bearing amino and urea functional groups have been applied for a novel, highly enantioselective synthesis of axially chiral isoquinoline N-oxides, which are promising chiral ligands or organocatalysts in organic synthesis. This is the first example of highly enantioselective synthesis of axially chiral biaryls by bifunctional organocatalysts. Good-to-excellent enantioselectivities were obtained with a range of substrates.
Selective Halogenation of Pyridines Using Designed Phosphine Reagents
作者:Jeffrey N. Levy、Juan V. Alegre-Requena、Renrong Liu、Robert S. Paton、Andrew McNally
DOI:10.1021/jacs.0c04674
日期:2020.6.24
metal complexes, but strategies to selectively halogenate pyridine C-H precursors are lacking. We designed a set of heterocyclic phosphines that are installed at the 4-position of pyridines as phosphonium salts and then displaced with halide nucleophiles. A broad range of unactivated pyridines can be halogenated, and the method is viable for late-stage halogenation of complex pharmaceuticals. Computational
A cephalosporin derivative of the formula I: ##STR1## in which X is S, O, CH.sub.2 or SO, R1 is (optionally-substituted)imidazol-2-yl or one of the C-7 acyl groups known in the cephalosporin art, R2 is hydrogen or methoxy, R3 is carboxy or a biodegradable ester thereof and --R4 is of the formula XII, XIII or XIV: ##STR2## in which R32-R40 inclusive are as defined in the specification; and the salts thereof. Pharmaceutical compositions, methods of manufacture and intermediates are also described.
A cephalosporin derivative of the formula I: ##STR1## in which X is S, O, CH.sub.2 or SO, R1 is (optionally-substituted) imidazol-2-yl or one of the C-7 acyl groups known in the cephalosporin art, R2 is hydrogen or methoxy, R3 is carboxy or a biodegradable ester thereof and -R4 is of the formula XII, XIII or XIV: ##STR2## in which R32-R40 inclusive are as defined in the specification; and the salts thereof. Pharmaceutical compositions, methods of manufacture and intermediates are also described.
Ruthenium(II)/Imidazolidine Carboxylic Acid‐Catalyzed C−H Alkylation for Central and Axial Double Enantio‐Induction
作者:Yanjun Li、Yan‐Cheng Liou、João C. A. Oliveira、Lutz Ackermann
DOI:10.1002/anie.202212595
日期:2022.11.21
Ruthenium(II)-catalyzed enantioselective C−H alkylations were realized with novel C2-symmetric chiral imidazolidine carboxylic acids, with high chemo-, regio-, diastereo-, and enantioselectivity. The C−H alkylation took place with simultaneous construction of central and axial chirality, reaching branched/linear ratios of >20 : 1 dr, and up to 98 : 2 er.