3-Ethoxycyclobutanones reacted with pyridines, quinolines, and isoquinolines to give the corresponding formal [4+2] cycloadducts, 9a-hydro-2H-quinolizin-2-one derivatives, by using Me3SiOTf in acetonitrile. Cycloaddition of 3-ethoxy-2-monoalkylcyclobutanones to 5-nitroquinoline or 4-cyanopyridine proceeded stereoselectively.
A Co-catalyzed highly chemo- and regio-selective nitration of C(sp3)-H was developed. Diverse aliphaticnitrocompounds were obtained in good yields, using t-BuONO as nitrating reagent. Specific nitration of C(sp3)-H instead of C(sp2)-H was achieved via a radical process rather than concerted metalation-deprotonation.
Formal [4+2] cycloaddition of 3-ethoxycyclobutanones with azo compounds
作者:Yusuke Shima、Jun-ichi Matsuo
DOI:10.1016/j.tetlet.2016.07.087
日期:2016.9
with EtAlCl2, and intermolecular formal [4+2] cycloaddition of the zwitterionic intermediate proceeded with azobenzenes to give 2,3-dihydro-pyridazin-4(1H)-ones after elimination of ethanol. Regioselectivity for cycloaddition of unsymmetrical azobenzenes, ring contraction and chemoselective reduction of 2,3-dihydro-pyridazin-4(1H)-ones, and [4+2] cycloaddition to 4-phenyl-1,2,4-triazolin-3,5-dione are
Collective Total Synthesis of Aspidofractinine Alkaloids through the Development of a Bischler–Napieralski/Semipinacol Rearrangement Reaction
作者:Shuang‐Hu Wang、Rui‐Qi Si、Qing‐Bo Zhuang、Xiang Guo、Tian Ke、Xiao‐Ming Zhang、Fu‐Min Zhang、Yong‐Qiang Tu
DOI:10.1002/anie.202009238
日期:2020.12
A tandem Bischler–Napieralski/semipinacol rearrangement reaction has been developed for the purpose of assembling a bis(spirocyclic) indole framework, a privileged structural unit of aspidofractinine‐type monoterpenoid indole alkaloids, and was used in combination with a subsequent Mannich reaction to expeditiously construct the central bridged bicyclo[2.2.1]heptane ring system of these molecules with
Transition-Metal-Free Access to Heteroaromatic-Fused 4-Tetralones by the Oxidative Ring Expansion of the Cyclobutanol Moiety
作者:Philipp Natho、Lewis A. T. Allen、Andrew J. P. White、Philip J. Parsons
DOI:10.1021/acs.joc.9b01290
日期:2019.8.2
Advances in the transition-metal-free cyclobutanol ringexpansion to 4-tetralones under N-bromosuccinimide mediation are described. We have expanded the scope of this ringexpansion methodology and investigated the effect substituents on the aromatic ring, and the cyclobutanol moiety, have on the outcome of the reaction. Limitations with certain substituents on the cyclobutanol moiety are also described