Selective reduction of carbonyl groups in the presence of low-valent titanium reagents
作者:Wei Lin、Ming-Hua Hu、Xian Feng、Lei Fu、Cheng-Pao Cao、Zhi-Bin Huang、Da-Qing Shi
DOI:10.1016/j.tetlet.2014.02.072
日期:2014.4
The chemoselective reduction of several structurally diverse compounds containing carbonyl groups was achieved in the presence of low-valenttitaniumreagents. This novel synthetic method provides easy access to highly selective reduction of carbonyl groups, and possesses several advantages including one-step procedure, convenient manipulation, good to excellent yields, and short reaction times.
The first inter- and intramolecular McMurry reactions of aroyltrimethylsilanes to substituted 1,2-bis(trimethylsilyl)ethene derivatives 2a-c and 7 are described. A low-valenttitanium reagent prepared by the reduction of TiCl3 with Na on inorganic supports (Al2O3, NaCl, TiO2) turned out to be best suited. Depending on the reaction conditions and on the particular substitution patterns of the substrates
描述了芳基三甲基硅烷与取代的1,2-双(三甲基甲硅烷基)乙烯衍生物2a-c和7的第一分子间和分子内McMurry反应。事实证明,通过在无机载体(Al 2 O 3,NaCl,TiO 2)上用Na还原TiCl 3制备的低价钛试剂是最合适的。根据反应条件和底物的特定取代方式,导致形成C,O-二甲硅烷基烯醇醚的中间体1,2-二甲硅烷基化的1,2-二醇钛酸酯的Brook重排可能与McMurry竞争脱氧途径。
Copper-Catalyzed <i>N</i>-Benzoylation of Amines via Aerobic C–C Bond Cleavage
A general copper/air catalytic system for selectively oxidative C–Cbondcleavage of 1,2-diarylethan-1-one has been developed, giving aromatic aldehydes and N-benzoylation products of various amines in moderate to excellent yields. This research provides an alternative approach for the N-benzoylation of amine in mild and neutral conditions.
By employing a chiral Lewis base as the catalyst, enantioselective hydrosilylation of N-(1,2-diarylethylidene)arylamines was realized. The reactions proceeded smoothly to afford various chiral 1,2-diarylethanamines with good yields (up to 99%) in good enantioselectivities (up to 98%). Furthermore, one of the products was employed in the synthesis of a pharmaceutical substance.