Rhodium(<scp>iii</scp>)-catalyzed C–H/C–C activation sequence: vinylcyclopropanes as versatile synthons in direct C–H allylation reactions
作者:Jia-Qiang Wu、Zhi-Ping Qiu、Shang-Shi Zhang、Jing-Gong Liu、Ye-Xing Lao、Lian-Quan Gu、Zhi-Shu Huang、Juan Li、Honggen Wang
DOI:10.1039/c4cc07839j
日期:——
Succession of C-Hactivation and C-Cactivation was achieved by using a single rhodium(III) catalyst. Vinylcyclopropanes were used as versatile coupling partners. Mechanistic studies suggest that the olefin insertion step is rate-determining and a facile beta-carbon elimination is involved, which represents a novel ring opening mode of vinylcyclopropanes.
An organocatalytic Cloke–Wilson rearrangement of cyclopropyl ketones to 2,3-dihydrofurans is exploited utilizing the homoconjugate addition process. With 1,4-diazabicyclo[2.2.2]octane as the catalyst, the rearrangement in DMSO at 120 °C proceeded in generally high yields, exclusive regioselectivity, and a broad substrate scope. An examination of the mechanism including stereochemical analysis and intermediate
Nickel-Catalyzed Rearrangement of 1-Acyl-2-vinylcyclopropanes. A Mild Synthesis of Substituted Dihydrofurans
作者:Roy K. Bowman、Jeffrey S. Johnson
DOI:10.1021/ol052700k
日期:2006.2.1
[reaction: see text] Mild Ni(0)-catalyzed rearrangements of 1-acyl-2-vinylcyclopropanes have been developed. The room-temperature isomerizations afford dihydrofuran products in yields regularly greater than 90%. A highly substituted, stereochemically defined cyclopropane was employed in the rearrangement to evaluate the reaction mechanism. Product analysis indicates that the overall reaction proceeds
We report a metal-, acid-, and base-free 2-(bromomethyl)naphthalene (2-BMN)-promoted organocatalytic Cloke–Wilson rearrangement of chain doubly activated cyclopropanes for the construction of 2,3-dihydrofurans via a carbocation-initiated tandem intramolecular ring-opening/recyclization process. The strategy is especially suitable for the construction of furan units in complex molecules, providing a
The Rh(III)-catalyzed C8-allylation of quinoline N-oxides has been accomplished using vinylcyclopropanes as an allyl source with excellent diastereoselectivity at room temperature. The C–H/C–Cactivation, substrate scope and natural product mutation are the important practical features.
Rh( III ) 催化的喹啉N-氧化物的 C8-烯丙基化已使用乙烯基环丙烷作为烯丙基源,在室温下具有出色的非对映选择性。C - H/C - C激活、底物范围和天然产物突变是重要的实用特征。