Details

Autor(en) / Beteiligte

• Lin, Hua-Chen
• Xie, Pei-Pei
• Dai, Zhen-Yao
• Zhang, Shuo-Qing
• Wang, Pu-Sheng
• Chen, Yu-Gen
• Wang, Tian-Ci
• Hong, Xin
• Gong, Liu-Zhu

Titel

Nucleophile-Dependent Z/E- and Regioselectivity in the Palladium-Catalyzed Asymmetric Allylic C–H Alkylation of 1,4-Dienes

Ist Teil von

• Journal of the American Chemical Society, 2019-04, Vol.141 (14), p.5824-5834

Ort / Verlag

United States: American Chemical Society

Erscheinungsjahr

2019

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The asymmetric allylic alkylation (AAA), which features employing active allylic substrates, has historical significance in organic synthesis. The allylic C–H alkylation is principally more atom- and step-economic than the classical allylic functionalizations and thus can be considered a transformative variant. However, asymmetric allylic C–H alkylation reactions are still scarce and yet underdeveloped. Herein, we have found that Z/E- and regioselectivities in the Pd-catalyzed asymmetric allylic C–H alkylation of 1,4-dienes are highly dependent on the type of nucleophiles. A highly stereoselective allylic C–H alkylation of 1,4-dienes with azlactones has been established by palladium-chiral phosphoramidite catalysis. The protocol proceeds under mild conditions and can accommodate a wide scope of substrates, delivering structurally divergent α,α-disubstituted α-amino acid surrogates in high yields and excellent levels of diastereo-, Z/E-, regio-, and enantioselectivities. Notably, this method provides key chiral intermediates for an efficient synthesis of lepadiformine marine alkaloids. Experimental and computational studies on the reaction mechanism suggest a novel concerted proton and two-electron transfer process for the allylic C–H cleavage and reveal that the Z/E- and regioselectivities are governed by the geometry and coordination pattern of nucleophiles.