Enantioselective Rauhut−Currier Reactions Promoted by Protected Cysteine
摘要:
We report highly enantioselective examples of the Rauhut-Currier cycloisomerization reaction (the "vinylogous Morita-Baylis-Hillman reaction"). The reaction is highly practical and is catalyzed by a commercially available derivative of the proteinogenic amino acid cysteine. Reactions are conducted in the presence of potassium tert-butoxide and a critical concentration of water in bulk acetonitrile. A mechanistic model is advanced that may account for reaction selectivity that is predicated on organizational chelation of K ion in the product-determining step in which the Cys derivative undergoes limination.
ortho-Acidic aromatic thiols as efficient catalysts of intramolecular Morita–Baylis–Hillman and Rauhut–Currier reactions
作者:Philipp S. Selig、Scott J. Miller
DOI:10.1016/j.tetlet.2010.11.077
日期:2011.4
ortho-Mercaptobenzoic acid and ortho-mercaptophenols were discovered as efficient thiol catalysts of both the intramolecular Morita–Baylis–Hillman (MBH) and Rauhut–Currier (RC) reaction. High reaction rates were achieved under mildly basic, aqueous conditions. The unprecedented catalytic activity of these protic nucleophiles could originate from a Brønsted acid induced destabilization of intermediate
showed good performance in enantioselectiveintramolecular Rauhut–Currier reaction of bis(enones), giving the corresponding products in good yield with up to 98% ee. Moreover, with amino acid derived amide-phosphine B3, optically active α-methylene-δ-valerolactone was obtained in 88% yield and > 99.9% ee utilizing the enantioselectiveintramolecular Rauhut-Currier reaction of chalcone derivative.
A Highly Nucleophilic Multifunctional Chiral Phosphane-Catalyzed Asymmetric Intramolecular Rauhut-Currier Reaction
作者:Xiao-Nan Zhang、Min Shi
DOI:10.1002/ejoc.201200940
日期:2012.11
An asymmetric variant of the intramolecularRauhut–Currier (RC) reaction can be achieved using a highlynucleophilicmultifunctionalchiral phosphane; the corresponding cyclopentene and cyclohexene derivatives are produced in moderate to good yields and with good to excellent enantioselectivities.
intramolecular Rauhut–Currier reaction of linear bis(enones) has been achieved via double activation catalysis of thiols and phase transfer substances, furnishing both enantioenriched cyclohexene and cyclopentene derivatives (up to 95% ee). Furthermore, the desymmetric version of prochiral substrates was developed under similar catalysis, producing the frameworks bearing an additional tertiary or even quaternary
Development of a Cysteine-Catalyzed Enantioselective Rauhut−Currier Reaction
作者:Carrie E. Aroyan、Alpay Dermenci、Scott J. Miller
DOI:10.1021/jo101018t
日期:2010.9.3
Herein, we report a full account of the development of an enantioselective Rauhut-Currier process that affords products in high yields and enantioselectivities using a cysteine-based catalyst. While traditional Morita-Baylis-Hillman catalysts were found to be essentially ineffective, various derivatives of protected cysteine were found to exhibit extraordinary reactivity and enantiotopic control. Extensive screening of reaction conditions led us to discover the enhanced effects of water as an additive and the chelating power of potassium in achieving higher enantiomer ratios. Mechanistic experiments also provided insight on the potential mechanism of the reaction in addition to possible transition states that provide the absolute stereochemistry formed in the observed products. Also included is a brief survey of the reaction scope involving different ring sizes as well as functionalized substrates.