Free Radical-Mediated Tandem Reaction of Dehydroamino Acid Derivative with π-Allyl Palladium Complex: Synthesis of α,α-Disubstituted Amino Acids
作者:Yoshiji Takemoto、Hideto Miyabe、Ryuta Asada、Kazumasa Yoshida
DOI:10.1055/s-2004-815407
日期:——
The diethylzinc-promoted reaction of dehydroamino acid derivative with electrophilic π-allylpalladium complex proceeded smoothly to afford α,α-disubstituted amino acids via a tandem radical and anionic carbon-carbon bondforming processes.
Synthesis of α,α-disubstituted amino acids based on tandem reaction of dehydroamino acid derivatives
作者:Hideto Miyabe、Ryuta Asada、Yoshiji Takemoto
DOI:10.1016/j.tet.2004.10.104
日期:2005.1
all-substituted sp3-hybridized carbon-center was investigated via tandem reaction of dehydroamino acid derivatives. The diethylzinc-promoted reaction of dehydroamino acid derivatives with acid anhydride or π-allylpalladium complex proceeded smoothly to afford α,α-disubstituted amino acids via a radical and anionic carbon–carbon bond-forming processes. The tandem reductive reaction of N-phthaloyl dehydroalanine
nickel and chiralamine cooperative catalysis to enable a highlyenantioselectiveallylic alkylation reaction between α-branched aldehydes and a wide scope of allyl esters, allowing the all-carbon quaternary stereocenter to be accessed with excellent enantioselectivity (up to 98% ee) and structural diversity. The general synthetic applicability has been showcased by the enantioselective synthesis of
全碳四元立体中心构成了天然产物和生物活性化合物的重要组成部分。在这里,我们公开了一种镍和手性胺协同催化,使 α-支化醛和各种烯丙基酯之间发生高度对映选择性的烯丙基烷基化反应,从而以优异的对映选择性(高达 98% ee ) 和结构多样性。关键手性构件的对映选择性合成以获取 (+)-依他佐辛、(-)-aphanorphine 和其他两种生物活性化合物,展示了一般合成适用性。
Kinetic Resolution of Racemic and Branched Monosubstituted Allylic Acetates by a Ruthenium-Catalyzed Regioselective Allylic Etherification
of racemic and branched monosubstituted allylicacetates by a ruthenium-catalyzed regioselective allylic etherification. The reaction was effectively catalyzed by the chiral ruthenium catalyst, which was generated by [RuCl2(p-cymene)]2 and (S,S)-iPr-pybox and a catalytic amount of TFA, and both the allylic etherification product and recovered allylicacetate were obtained as an enantiomerically enriched
transition-metal-catalyzed allylicsubstitution was examined. The oxygen atom of oxime acted as a reactive nucleophile in the reaction of a π-allyl palladium complex. In the presence of Pd(PPh3)4, the allylicsubstitution of oximes with allylic carbonate afforded the linear O-allylated oxime ethers selectively without a base. In contrast, the palladium-catalyzed reaction with allylic acetate proceeded smoothly
考察了肟作为亲核试剂在过渡金属催化的烯丙基取代中的活力。肟的氧原子在π-烯丙基钯配合物的反应中充当反应性亲核试剂。在Pd(PPh 3)4存在下,用碳酸烯丙酯进行肟的烯丙基取代,可选择性地得到线性的O-烯丙基化肟醚,而无需碱。相反,在存在K 2 CO 3或Et 2 Zn作为碱的情况下,钯与乙酸烯丙酯的反应顺利进行。通过使用钯(II)催化剂选择性地形成硝酮。在Pd(cod)Cl 2存在下通过与肟的氮原子反应,在无溶剂条件下,用乙酸烯丙酯将肟的烯丙基取代提供了N-烯丙基化的硝酮。