描述了由(杂)芳基甲基酮催化合成α-氟化手性叔醇的对映体。发现使用双功能亚氨基正膦(BIMP)超碱可通过提供快速形成芳基烯醇酸酯所需的强布朗斯台德碱度,促进直接添加羟醛。新的合成方案易于执行,并具有高对映选择性(高达> 99:1 er),可耐受各种功能和杂环。已经证明了多克的可扩展性以及催化剂的回收和再循环。1 H NMR研究表明,与现有技术水平的催化体系相比,BIMP催化的速率提高了1400倍。通过合成各种对映体丰富的结构单元和杂环,突出了醛醇产品的实用性,其中包括:
Chemo‐ and Enantioselective Intramolecular Silver‐Catalyzed Aziridinations
作者:Minsoo Ju、Cale D. Weatherly、Ilia A. Guzei、Jennifer M. Schomaker
DOI:10.1002/anie.201704786
日期:2017.8.7
nitrene-transfer reactions are a powerful tool for the preparation of enantioenriched amine building blocks. Reported herein are chemo- and enantioselective silver-catalyzed aminations which transform di- and trisubstituted homoallylic carbamates into [4.1.0]-carbamate-tethered aziridines in good yields and with ee values of up to 92 %. The effects of the substrate, silver counteranion, ligand, solvent, and
(4+3) Annulation of Donor‐Acceptor Cyclopropanes and Azadienes: Highly Stereoselective Synthesis of Azepanones
作者:Stefano Nicolai、Jérôme Waser
DOI:10.1002/anie.202209006
日期:2022.9.5
Azepanones are important and widespread seven-membered heterocycles, but their synthesis is challenging. A convergent method to access these scaffolds was developed relying on a (4+3) annulation reaction of azadienes and donor-acceptor cyclopropanes. Good to excellent yields and high diastereoselectivity were achieved using Yb(OTf)3 as the catalyst. Asymmetric induction was possible with Cu(OTf)2 in
Bifunctional Iminophosphorane‐Catalyzed Enantioselective Nitroalkane Addition to Unactivated α,β‐Unsaturated Esters
作者:Daniel Rozsar、Alistair J. M. Farley、Iain McLauchlan、Benjamin D. A. Shennan、Ken Yamazaki、Darren James Dixon
DOI:10.1002/anie.202303391
日期:——
The first intermolecular enantioselectiveaddition of nitroalkanes to unactivated α,β-unsaturated esters is described, catalyzed by a bifunctional iminophosphorane (BIMP) superbase. This fundamental synthetically relevant transformation proceeds with high enantiomeric excesses and yields over a wide range of feedstock substrates, providing pharmaceutically relevant building blocks in a single step
Synthesis of chiral C/N-functionalized morpholine alcohols: study of their catalytic ability as ligand in asymmetric diethylzinc addition to aldehyde
作者:Rajesh Dave、N. André Sasaki
DOI:10.1016/j.tetasy.2005.12.027
日期:2006.2
A broad variety of chiral C/N-functionalized morpholine alcohols sharing a common structural motif in the 3-(hydroxy-methyl)morpholine 6 were prepared froin criantiomerically pure serine for the purpose of studying their catalytic ligand properties. The asymmetric addition of diethylzinc to benzaldehyde in the presence of 10 mol % of chiral C/N-functionalized morpholine alcohols gave 1-phenyl-1-propanol in 59-81% yield with 10-30% ee. The addition of 10 mol % of n-butyl lithium to the reaction mixture resulted in a significant enhancement of the stereoselectivity in the case of ligands bearing the two geminal phenyl substituents on the backbone. In the presence of n-butyl lithium and using (S)-3-(hydroxydiphcnylmethyl)morpholine (S)-19 as the chiral promoter, (S)-1-phenyl-1 -propanol was obtained in 81% yield with 76% ee. The geminal diphenyl-class of morpholine ligands was examined for the diethylzinc addition to four different aldehydes in the presence of n-butyl lithium. (S)-N-Benzyl-3-(hydroxydiphenymethyl)morpholine (S)-27 was found to be most enantioselective in the case of 4-metlioxybenzaldehyde to give (R)-alcohol in 87K yield with 80% ee. Catalysts (S)-19 and its N-methyl derivative (S)-26 gave alcohols with an (S)-absolute configuration while the N-benzylated derivative (S)-27 gave the opposite enantiomeric products. The tentative transition state models to account for the observed product stereoselectivity with morpholine ligands holding the geminal diphenyl group on the beta-amino alcohol segment are proposed. (c) 2006 Elsevier Ltd. All rights reserved.
Stereocontrolled Conversion of L-Serine into a Series of Valuable Unnatural α-Amino Acids