RESUMO
A single nucleotide polymorphism (SNP) base on the target is displayed at a gap in a ternary duplex carrying beta-cyclodextrin-modified DNA. A stable tandem duplex forms regardless of the type of SNP base. A nucleobase-specific ligand is then added to this system. The dansyl moiety in the ligand is expected to form a luminous inclusion complex with nearby beta-CyD, only when the ligand recognizes the specific base displayed in the gap.
Assuntos
Sondas de DNA/química , DNA/química , Corantes Fluorescentes/química , beta-Ciclodextrinas/química , Ligantes , Modelos Moleculares , Estrutura Molecular , Espectrofotometria , Especificidade por SubstratoRESUMO
Palladium-diethylzinc or palladium-triethylborane catalytically promotes self-allylation of 2-(allyloxy)tetrahydrofurans, 2-(allyloxy)tetrahydropyrans, and their hydroxy derivatives on the rings (ribose, glucose, mannose, deoxyribose, deoxyglucose). All the reactions proceed at room temperature and provide polyhydroxyl products, sharing a structural motif of a homoallyl alcohol, in good to excellent yields with high levels of stereoselectivity. Useful C3-unit elongation, which makes the best use of an allyl ether as a protecting group and a nucleophilic allylation agent, is demonstrated. Mechanisms for the umpolung reaction (of an allyl ether into an allylic anion) and stereoselectivity associated with allylation of aldehydes are discussed.
Assuntos
Aldeídos/síntese química , Compostos Alílicos/química , Ésteres/química , Furanos/química , Compostos Organometálicos/química , Paládio/química , Piranos/química , Alquilação , Catálise , Cristalografia por Raios X , Modelos Moleculares , Estrutura Molecular , Estereoisomerismo , Zinco/químicaRESUMO
A catalytic system, Pd(OAc)2 (10 mol %)-P(n-Bu)3 (20 mol %)-Et3B (360 mol %), promotes allylic alcohols to undergo the allylation of anisidine-imines of aromatic and aliphatic aldehydes and furnishes homoallylamines in good to moderate yields. The reaction shows unique stereoselectivity, giving anti-isomers selectively. [reaction: see text]
RESUMO
Regio- and stereoselective homoallylation of saturated aldehydes and ketones to give bishomoallyl alcohols 1,3-anti-1 is achieved with [Ni(acac)2 ] (cat.) and Et2 Zn [Eq. (a)]. This new catalyst system thus complements the previously reported combination of [Ni(acac)2 ] with Et3 B, which offers advantages in the homoallylation of unsaturated and aromatic aldehydes. acac=acetylacetonato.
