Cu(II)-catalyzed enantioselective 1,3-dipolar cycloaddition of nitrones with α, β-unsaturated acyl phosphonates
作者:Lei Xie、Hui Bai、Jiaqi Li、Xuan Yu、Zhenhua Zhang、Bin Fu
DOI:10.1016/j.tet.2017.03.086
日期:2017.5
A highly enantioselective 1, 3-dipolar cycloaddition of nitrone with α, β-unsaturated acyl phosphonate was developed for the first time by using a chiral indane-bis(oxazoline)-copper(II) complex. The reaction proceeded smoothly under mild conditions to provide isoxazolidines with multi-stereocenters in good yields with high to excellent diastereo- (>20:1 dr) and enantioselectivities (up to 99% ee)
arylnitrones and diazo compounds by C–H activation/[4 + 1] annulation with a C(N2)–C(acyl) bond cleavage is reported, and 2,3-disubstituted NH indoles are directly synthesized in up to a 94% yield. A variety of functional groups are applicable to this reaction to give the corresponding products with high selectivity. Compared to other previously reported Rh(III)-catalyzed synthesis of homologous series, this method
Rhodium(II)- and Copper(II)-Catalyzed Reactions of Enol Diazoacetates with Nitrones: Metal Carbene versus Lewis Acid Directed Pathways
作者:Yu Qian、Xinfang Xu、Xiaochen Wang、Peter J. Zavalij、Wenhao Hu、Michael P. Doyle
DOI:10.1002/anie.201202525
日期:2012.6.11
A complimentary cat.: Copper(II) hexafluoroantimonate catalyzes the formal [3+3] cycloaddition of Lewisacid activated nitrones and vinyl diazoacetates to produce 3,6‐dihydro‐1,2‐oxazines in yields of up to 96 % and diastereoselectivities greater than 25:1 (see scheme). This process compliments the metalcarbenepathway that is catalyzed by rhodium(II) species.
ABSTRACT An efficient Strecker-type reaction of nitrones with trimethylsilyl cyanide (TMSCN) catalyzed by MgI2 etherate has been achieved in a short time under mild condition. The condensations of aromatic nitrones, heterocyclic nitrones, and aliphatic nitrones with TMSCN are performed in good to excellent yields. Further dehydration of α-cyanohydroxylamine smoothly produced the α-imine nitrile in
Catalytic Asymmetric Cycloaddition Reaction of Alkenyl Trichloroacetates with Nitrones
作者:Akira Yanagisawa、Atsuto Izumiseki、Takuya Sugita、Naoyuki Kushihara、Kazuhiro Yoshida
DOI:10.1055/s-0031-1290094
日期:2012.1
(S)-BINOL-derived chiral tindibromide possessing a 4-trifluoromethylphenyl group at 3- and 3′-positions as the chiral precatalyst in the presence of sodium ethoxide, sodium iodide, and ethanol. Optically active isoxazolidines with up to 95% ee were diastereoselectively obtained in high yields even from aliphatic aldehyde derived nitrones under the influence of the in situ generated chiral tin ethoxide iodide