3-substituted indoles with diazoenals furnished privileged pyrido[1,2-a]indoles. The reaction is proposed to involve a [4 + 2]-annulation of the diacceptor rhodium enalcarbenoid via C-2 functionalization of the indole. The utility of the methodology was demonstrated with a short synthesis of the tetrahydropyrido[1,2-a]indole core, present in a large number of biologically important polycyclic indole alkaloids
一种新颖的铑催化3-取代的吲哚与重氮烯的吡啶鎓吡啶环反应,并提供了优先的吡啶并[1,2- a ]吲哚。提出该反应涉及通过吲哚的C-2官能化使二受体铑烯醛烯类化合物[4 + 2]环化。该方法的实用性通过四氢吡啶并[1,2- a ]吲哚核的短合成得到证明,该四氢吡啶并[1,2- a ]吲哚核存在于大量生物学上重要的多环吲哚生物碱中。
Rh(II) acetate catalyzed cyclopropanation of styrenes with enaldiazo esters: diastereoselective synthesis of enal-cyclopropanes
作者:Kuldeep Singh Rathore、Sreenivas Katukojvala
DOI:10.1016/j.tetlet.2014.09.126
日期:2014.11
An efficient Rh(II) acetate catalyzed highly diastereoselective cyclopropanation of styrenes with enaldiazo esters has been developed (up to >95:5 dr and 62-82% yield). The reaction is proposed to involve diacceptor electrophilic rhodium enalcarbenoids and constitutes the first direct synthesis of enal-cyclo-propanes with an all carbon 7-quaternary stereocenter. (C) 2014 Elsevier Ltd. All rights reserved.