Highly enantioselective hydrogenation of various N-Boc-indoles proceeded successfully in the presence of the ruthenium complex generated from an appropriate ruthenium precursor and a trans-chelate chiral bisphosphine PhTRAP. Various 2- or 3-substituted indoles were converted into chiral indolines with high enantiomeric excesses (up to 95% ee). The PhTRAP-ruthenium catalyst was able to promote the hydrogenation of 2,3-dimethylindoles, giving cis-2,3-dimethylindolines with 72% ee.
Catalytic asymmetric hydrogenation of N-Boc-protected pyrroles proceeded with high enantioselectivity by using a ruthenium catalyst modified with a trans-chelating chiral bisphosphine PhTRAP. The ruthenium catalyst prepared from Ru(eta3-methallyl)2(cod) and (S,S)-(R,R)-PhTRAP in the presence of triethylamine was the most enantioselective for the asymmetric hydrogenation of methyl pyrrole-2-carboxylate, giving the desired (S)-proline derivative with 79% ee in 92% yield. Moreover, 2,3,5-trisubstituted pyrroles bearing a large substituent at the 5-position were hydrogenated with 93-99.7% ee. The asymmetric reduction of 4,5-dimethylpyrrole-2-carboxylate gave only all-cis isomer and created three chiral centers with high degree of stereocontrol in a single process. This is the first highly enantioselective reduction of pyrroles.
Vanishing aromaticity: A chiral ruthenium complex catalyzes the hydrogenation of 2,6‐ or 2,7‐disubstituted naphthalenes to give chiral tetralins with up to 92 % ee. The chiral catalyst is applicable to the regio‐ and enantioselective reduction of 6‐substituted 2‐alkoxynaphthalenes and preferentially hydrogenates the alkoxy‐substituted arene rings.
Various bisindolylmaleimides have fluorescence emission maxima wavelengths longer than 500 nm, large Stokes shifts longer than 200 nm, different fluorescence emission wavelengths at an excitation wavelength of 365 nm, and a long-lasting chemiluminescence. The expansion of the pi-conjugation, the pi-bond electronic structure, and oxidation of the C=C bond at the 2,3-position of the maleimide moiety are crucial for producing these fluorescence and chemiluminescence properties.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.