Studies on Pd(II)-Catalyzed Coupling−Cyclization of α- or β-Amino Allenes with Allylic Halides
摘要:
The palladium-catalyzed coupling-cyclization of alpha- or beta-amino allenes with allylic halides leading to 3-allylic 2,5-dihydropyrroles and 1,2,3,6-tetrahydropyridines, respectively, was studied. The starting materials are easily available. The skeletons of both two classes of products were established by the X-ray diffraction studies of 7i and 9b. Through the study of the reaction of 2b with 3-chloro-1-butene, 1-chloro-2-butene, and pi-allyl palladium species and the stereochemical outcome of the coupling cyclization of (S)-2m and (R)-2n, it is believed that the current transformation most likely proceeded via a Pd(II)-catalyzed pathway, although a Pd(0) pathway cannot be completely excluded.
Enantioselective Synthesis of Allenes by Catalytic Traceless Petasis Reactions
作者:Yao Jiang、Abdallah B. Diagne、Regan J. Thomson、Scott E. Schaus
DOI:10.1021/jacs.6b11937
日期:2017.2.8
Allenes are useful functional groups in synthesis as a result of their inherent chemical properties and established reactivity patterns. One property of chemical bonding renders 1,3-substituted allenes chiral, making them attractive targets for asymmetric synthesis. While there are many enantioselective methods to synthesize chiral allenes from chiral starting materials, fewer methods exist to directly
through synergistic Pd/Cu-catalyzed dynamic kinetic asymmetricallenylation with racemic allenylic esters. The protocol is suitable for a wide range of substrates including the challenging allenylic esters with less sterically bulky substituents and provided chiral allenylic products bearing 1,3-nonadjacent stereocenters with high levels of enantio- and diastereoselectivities (up to >20:1 dr and >99% ee)
General CuBr<sub>2</sub>-catalyzed highly enantioselective approach for optically active allenols from terminal alkynols
作者:Xin Huang、Tao Cao、Yulin Han、Xingguo Jiang、Weilong Lin、Jiasheng Zhang、Shengming Ma
DOI:10.1039/c5cc00697j
日期:——
A copper(ii) bromide-catalyzed highly enantioselective direct synthesis of 1,3-disubstituted allenols from commercially available aldehydes, terminal alkynols and (R)- or (S)-α,α-diphenylprolinol has been developed.
A Rhodium(I)-Catalyzed Formal Allenic Alder Ene Reaction for the Rapid and Stereoselective Assembly of Cross-Conjugated Trienes
作者:Kay M. Brummond、Hongfeng Chen、Peter Sill、Lingfeng You
DOI:10.1021/ja027588p
日期:2002.12.1
A rhodium(I)-catalyzed allenic Alderenereaction to prepare cross-conjugated trienes has been discovered. The scope and limitations are currently being investigated, and the results obtained to date are reported on. This method shows enticing functional group compatibility by tolerating terminal and internal alkynes, hydroxyl, sulfonamide, ether, and diester groups. Progress has been made to increase
Control of Regioselectivity in Pd(0)-Catalyzed Coupling−Cyclization Reaction of 2-(2‘,3‘-Allenyl)malonates with Organic Halides
作者:Shengming Ma、Ning Jiao、Shimin Zhao、Hairong Hou
DOI:10.1021/jo0108616
日期:2002.5.1
in the Pd(0)-catalyzed coupling-cyclization of 2-(2',3'-allenyl)malonates with organichalides is determined by the steric and electronic effects of both substrates. By deliberate control of the reaction conditions, the regioselectivity of this reaction can be tuned. With conditions A and B, the reaction afforded vinylic cyclopropane derivatives, while with conditions C and D, the reaction afforded