development of expeditious methods to synthesize these skeletons remains a challenging task. In this work, the catalyticcyclization of biomass-derived 2-furylcarbinols with an azide to form fused triazoles is described. This approach takes advantage of a single catalyst Yb(OTf)3 and operates via a furfuryl-cation-induced intramolecular [3 + 2] cycloaddition/furan ring-opening cascade.
The first asymmetric decarboxylative [4 + 3] annulation of propargylic carbamates with C, N-cyclic azomethineimines has been developed successfully by a copper- N-heterocyclic carbine system. This strategy led to a series of optically active isoquinoline-fused triazepine derivatives in good yields and with excellent enantio- and diastereoselectivities. Remarkably, Cu-allenylidene intermediates play
A Phosphine-Catalyzed Novel Asymmetric [3+2] Cycloaddition of C,N-Cyclic Azomethine Imines with δ-Substituted Allenoates
作者:De Wang、Yu Lei、Yin Wei、Min Shi
DOI:10.1002/chem.201405191
日期:2014.11.17
asymmetric [3+2] cycloadditions of C,N‐cyclic azomethine imines with δ‐substituted allenoates have been developed in the presence of (S)‐Me‐f‐KetalPhos, affording functionalized tetrahydroquinoline frameworks in good yields with high diastereo‐ and good enantioselectivities under mild condition. The substrate scope has been also examined. This is the first time that δ‐substituted allenoates have been
Ionic hydrogenation has not been extensively explored, but is advantageous for challenging substrates such as unsaturated intermediates. Reported here is an iridium-catalyzedhydrogenation of oxocarbenium ions to afford chiral isochromans with high enantioselectivities. A variety of functionalities are compatible with this catalytic system. In the presence of a catalytic amount of the Brønsted acid
CuBr2 catalyzed bromination/oxidation of isochromans to benzaldehyde derivatives
作者:Mei-Yan Zhou、Shan-Shan Kong、Ling-Qiong Zhang、Ming Zhao、Jin-Ao Duan、Zhen Ou-yang、Min Wang
DOI:10.1016/j.tetlet.2013.05.078
日期:2013.7
A series of isochromans were oxidized and brominated by using 1.2 equiv of CuBr2 in CH3CN at reflux to give the corresponding bromo benzaldehydes in moderate yields. A plausible mechanism for this transformation has been suggested. (C) 2013 Elsevier Ltd. All rights reserved.