RESUMO
The asymmetric addition of lithium acetylides to carbonyl compounds in the presence of a chiral lithium binaphtholate catalyst was developed. A procedure involving the slow addition of carbonyl compounds to lithium acetylides improved the enantioselectivity. This reaction afforded diverse chiral secondary and tertiary propargylic alcohols in high yields and with good to high enantioselectivities.
Assuntos
Álcoois/química , Álcoois/síntese química , Compostos de Lítio/química , Naftalenos/química , Pargilina/análogos & derivados , Pargilina/química , Pargilina/síntese química , Catálise , Estrutura Molecular , EstereoisomerismoRESUMO
Staphylococcus aureus is a major human pathogen that can colonize the nasal cavity, skin, intestine, and oral cavity as a commensal bacterium. gp340, also known as DMBT1 (deleted in malignant brain tumors 1), is associated with epithelial differentiation and innate immunity. In the oral cavity, gp340 induces salivary aggregation with several oral bacteria and promotes bacterial adhesion to tissues such as the teeth and mucosa. S. aureus is often isolated from the oral cavity, but the mechanism underlying its persistence in the oral cavity remains unclear. In this study, we investigated the interaction between S. aureus and gp340 and found that S. aureus interacts with saliva- and gp340-coated resin. We then identified the S. aureus factor(s) responsible for binding to gp340. The cell surface protein SasA, which is rich in basic amino acids (BR domain) at the N terminus, was responsible for binding to gp340. Inactivation of the sasA gene resulted in a significant decrease in S. aureus binding to gp340-coated resin. Also, recombinant SasA protein (rSasA) showed binding affinity to gp340, which was inhibited by the addition of N-acetylneuraminic acid. Surface plasmon resonance analysis showed that rSasA significantly bound to the NeuAcα(2-3)Galß(1-4)GlcNAc structure. These results indicate that SasA is responsible for binding to gp340 via the N-acetylneuraminic acid moiety.
Assuntos
Proteínas de Bactérias/metabolismo , Fosfotransferases/metabolismo , Receptores de Superfície Celular/metabolismo , Staphylococcus aureus/enzimologia , Proteínas de Bactérias/química , Proteínas de Bactérias/genética , Proteínas de Ligação ao Cálcio , Proteínas de Ligação a DNA , Regulação Bacteriana da Expressão Gênica/fisiologia , Humanos , Masculino , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Pessoa de Meia-Idade , Mutação , Ácido N-Acetilneuramínico/química , Fosfotransferases/química , Ligação Proteica , Receptores de Superfície Celular/química , Receptores de Superfície Celular/isolamento & purificação , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Saliva/química , Staphylococcus aureus/genética , Staphylococcus aureus/metabolismo , Proteínas Supressoras de TumorRESUMO
Chiral lithium binaphtholate effectively catalyzed the enantioselective alkynylation of ketones using lithium acetylide as an alkynylating agent. This is the first example of the catalytic enantioselective addition of lithium acetylide to carbonyl compounds without the aid of other metal sources.