The first direct asymmetricvinylogousMannich (AVM) reaction of alpha,alpha-dicyanoolefins and N-Boc aldimines was described promoted by a simple chiral bifunctional thiourea-tertairy amine organocatalyst. The reaction was highlyefficient (S/C up to 1000) and regio-, stereoselective (generally >99% de, 96 to >99.5% ee) at room temperature for a broad array of substrates. Enantiomerically pure delta-amino
The first highly enantioselective allylic–allylic alkylation of α,α‐dicyanoalkenes and Morita–Baylis–Hillman carbonates by dualcatalysis of (DHQD)2AQN and (S)‐BINOL has been investigated. Excellent stereoselectivities have been achieved for a broad spectrum of substrates (d.r. > 99:1, up to 99 % ee). The multifunctional allylic products could be efficiently converted to a range of complex chiral cyclic
Visible-Light-Mediated Intermolecular Radical Conjugate Addition for the Construction of Vicinal Quaternary Carbon Centers
作者:Lei Li、Lili Fang、Weiping Wu、Jin Zhu
DOI:10.1021/acs.orglett.0c01724
日期:2020.7.17
The visible light-driven organophotoredox catalysis is reported for the construction of vicinal quaternary carbon centers. Intermolecular conjugateaddition of alkyl radicals, derived from 2,2-disubstituted dihydroquinazolinones, to Michael acceptors under blue light irradiation and rhodamine B catalysis allows the facile assembly of diverse, vicinal secondary/quaternary, tertiary/quaternary, and
A Convenient and Selective One-Pot Method for the Synthesis of Monosubstituted Secondary Alkyl Malononitriles
作者:Robert Sammelson、Mark Allen
DOI:10.1055/s-2004-837290
日期:——
We have found that α,α-dicyanoalkenes can be efficiently and selectively reduced to α,α-dicyanoalkanes (malononitriles) with NaBH4 in 95% EtOH at 0 °C. In addition, we have determined that the condensation of malononitrile with ketones using absorption alumina as a catalyst can be followed directly, in one pot, by reduction with NaBH4 in 95% EtOH at 0 °C to provide the monosubstituted secondary alkyl malononitriles in good to excellent yields (42-94%). This procedure provides a convenient alternative to direct alkylation of malononitrile or reduction of α,α-dicyanoalkene intermediates.
Complex Hydroindoles by an Intramolecular Nitrile-Intercepted Allylic Alkylation Cascade Reaction
作者:Peter Vertesaljai、Ion Ghiviriga、Alexander J. Grenning
DOI:10.1021/acs.orglett.8b00499
日期:2018.4.6
Bisnucleophilic reagents derived from malononitrile, ketones, benzaldehydes, and nitromethane can react with bisallylic electrophiles via a nitrile-intercepted allylic alkylation cascade reaction to yield complex hydroindole architectures. Also noteworthy is that the only stoichiometric byproducts from the preparation and reaction of the bisnucleophile and biselectrophile are water, acetic acid, and