- Electroreductive coupling of aromatic ketones, aldehydes, and aldimines with α,β-unsaturated esters: Synthesis of 5-aryl substituted γ-butyrolactones and lactams
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The electroreductive intermolecular coupling of aromatic ketones and aldehydes with α,β-unsaturated esters in the presence of TMSCl gave the adducts as γ-trimethylsiloxy esters. The detrimethylsilylation of the adducts with TBAF afforded 5-aryl substituted γ-butyrolactones. The electroreductive coupling of N-(4-methoxyphenyl)-1-arylmethaneimines with methyl acrylate in the presence of TMSCl gave the adducts as methyl 4-aryl-4-((4-methoxyphenyl)amino)butanoates. The adducts were transformed to 5-aryl-γ-butyrolactams by cyclization with NaH and subsequent oxidation with CAN. (±)-Norcotinine was prepared from nicotinaldehyde by this method. The electroreductive coupling of aromatic ketones and aldimines with acrylonitrile in the presence of TMSCl gave 4-aryl-4-(trimethylsiloxy)butanenitriles and 4-aryl-4-((4-methoxyphenyl)amino)butanenitriles, respectively.
- Kise, Naoki,Hamada, Yusuke,Sakurai, Toshihiko
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p. 1143 - 1156
(2017/02/18)
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- Ring Opening of Donor-Acceptor Cyclopropanes with the Azide Ion: A Tool for Construction of N-Heterocycles
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A general method for ring opening of various donor-acceptor cyclopropanes with the azide ion through an SN2-like reaction has been developed. This highly regioselective and stereospecific process proceeds through nucleophilic attack on the more-substituted C2 atom of a cyclopropane with complete inversion of configuration at this center. Results of DFT calculations support the SN2 mechanism and demonstrate good qualitative correlation between the relative experimental reactivity of cyclopropanes and the calculated energy barriers. The reaction provides a straightforward approach to a variety of polyfunctional azides in up to 91% yield. The high synthetic utility of these azides and the possibilities of their involvement in diversity-oriented synthesis were demonstrated by the developed multipath strategy of their transformations into five-, six-, and seven-membered N-heterocycles, as well as complex annulated compounds, including natural products and medicines such as (-)-nicotine and atorvastatin. A new world of opportunities: Stereospecific ring opening of donor-acceptor cyclopropanes with the azide ion gives rise to densely functionalized building blocks that are valuable for the assembly of a diverse range of N-heterocycles (see scheme; EDG=electron donating group; EWG=electron withdrawing group). These synthetic opportunities are provided by the simultaneous presence of the N3 group, which reacts as a latent amine or 1,3-dipole, easily modifiable donor and acceptor substituents, as well as the activated CH fragment.
- Ivanov, Konstantin L.,Villemson, Elena V.,Budynina, Ekaterina M.,Ivanova, Olga A.,Trushkov, Igor V.,Melnikov, Mikhail Ya.
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p. 4975 - 4987
(2015/03/18)
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