through a hydrazine-directed C–H functionalization pathway. This [4+1] annulation, based on the cleavage of a Csp–Csp triple bond in alkynylcyclobutanol, provides a new pathway to prepare diverse 1H-indazoles under mild reaction conditions.
Abstract An efficient Rh-(III)-catalyzed C-H functionalization of N-ethoxybenzamides with 1-alkynylcyclobutanols has been developed. Isoquinolone derivatives have been successfully synthesized through [4 + 2] annulation and ring opening reaction under mild conditions. The advantages of this efficient protocol include broad substrate scope and good to excellent yields. Graphical Abstract
Synthesis of Indolyl-Tethered Spiro[cyclobutane-1,1′-indenes] through Cascade Reactions of 1-(Pyridin-2-yl)-1<i>H</i>-indoles with Alkynyl Cyclobutanols
作者:Yuanshuang Xu、Caiyun Yu、Xinying Zhang、Xuesen Fan
DOI:10.1021/acs.orglett.1c03200
日期:2021.11.5
herein is an efficient and unprecedented synthesis of indolyl-tethered spiro[cyclobutane-1,1′-indenes] through the cascade reaction of 1-(pyridin-2-yl)-1H-indoles with alkynyl cyclobutanols. Mechanistic experiments implicate a sequential process in which 1-(pyridin-2-yl)-1H-indole first undergoes an alkenylation with alkynyl cyclobutanol followed by an intramolecular Friedel–Crafts reaction to give the
efficient and straightforward approach for the synthesis of C7 site-selective BINOL derivatives has been achieved via cost-effective Co(III)-catalyzed C–Hcascadealkenylation/intramolecular Friedel–Crafts alkylation of BINOL units and propargyl cycloalkanols. Under the advantage of the pyrazole directing group, the protocol allows the rapid synthesis of various BINOL-tethered spiro[cyclobutane-1,1′-indenes]
A Rhodium(III)-catalyzed [4+1] annulation and ring opening of 1 alkynylcyclobutanols with pyrazolidinones to access pyrazolo[1,2-a] indazoles bearing a quaternary carbon center was described. This method features high functional group tolerability and afforded pyrazolo[1,2-a] indazoles in moderate to good yield under mild conditions. (C) 2020 Elsevier Ltd. All rights reserved.