Palladium/monophosphine complexes catalyze trans-selective arylative, alkenylative, and alkylativecyclization reactions of alkynals and alkynones with organoboronic reagents. These reactions afford six-membered allylic alcohols with endo-tri- or tetrasubstituted olefin groups and/or five-membered counterparts with exo olefin groups. The ratios of these products are dramatically affected by alkyne
Gold-Catalyzed Oxidative Cycloadditions to Activate a Quinoline Framework
作者:Deepak B. Huple、Satish Ghorpade、Rai-Shung Liu
DOI:10.1002/chem.201302533
日期:2013.9.23
gold! Gold‐catalyzed reactions of 3,5‐ and 3,6‐dienynes with 8‐alkylquinoline oxides results in an oxidative cycloaddition with high stereospecificity (see scheme; EWG = electron‐withdrawing group); this process involves a catalytic activation of a quinoline framework. The reaction mechanism involves the intermediacy of α‐carbonyl pyridinium ylides (I) in a concerted [3+2]‐cycloaddition with a tethered
Syntheses of 12<i>H</i>-benzo[<i>a</i>]xanthen-12-ones and benzo[<i>a</i>]acridin-12(7<i>H</i>)-ones through Au(<scp>i</scp>)-catalyzed Michael addition/6-<i>endo</i>-trig cyclization/aromatization cascade annulation
cascade cyclization strategy to synthesize both 12H-benzo[a]xanthen-12-ones and benzo[a]acridin-12(7H)-ones, whose core motifs xanthone and acridone both exist as important scaffolds in an immense number of bioactive compounds, was developed. The scopes of this strategy were examined by using a batch of synthetic 1,3-diphenylprop-2-yn-1-one substrates. To probe the mechanism of this cyclization a control
一种多面金(I)催化芳香性驱动的双6-内联双级环化策略,可合成其核心的12 H-苯并[ a ]黄嘌呤-12-酮和苯并[ a ] ac啶-12(7 H)-酮开发了基序黄酮和and啶酮,它们作为重要的支架存在于大量的生物活性化合物中。通过使用一批合成的1,3-二苯基丙-2-yn-1-one底物检查了该策略的范围。为了探索这种环化的机理,进行了合成中间体的对照实验。因此,根据该实验和先前的研究确定了推定的机制。
Catalytic Cyclization of
<i>o</i>
‐Alkynyl Phenethylamines via Osmacyclopropene Intermediates: Direct Access to Dopaminergic 3‐Benzazepines
作者:Andrea Álvarez‐Pérez、Carlos González‐Rodríguez、Cristina García‐Yebra、Jesús A. Varela、Enrique Oñate、Miguel A. Esteruelas、Carlos Saá
DOI:10.1002/anie.201505782
日期:2015.11.2
A novel osmium‐catalyzed cyclization of o‐alkynylphenethylamines to give 3‐benzazepines is reported. The procedure allows the straightforward preparation of a broad range of dopaminergic3‐benzazepine derivatives. Mechanistic investigations revealed that the process takes place viaosmacyclopropeneintermediates, which were isolated and characterized by X‐ray crystallography.
The synthesis of several natural products’ frameworks is carried out by means of a diastereoselective intramolecular Pauson–Khand reaction promoted by molecular sieves. Diastereoselectivity is achieved only if a coordinating group is present at a convenient distance from the alkene moiety. Naphthalenes can be obtained directly under refluxing toluene conditions.