Generation and Alkylation of α-Carbamyl Radicals via Organic Photoredox Catalysis
作者:Joshua B. McManus、Nicholas P. R. Onuska、David A. Nicewicz
DOI:10.1021/jacs.8b04890
日期:2018.7.25
Strategies for the direct C-H functionalization of amines are valuable as these compounds comprise a number of pharmaceuticals, agrochemicals and natural products. This work describes a novel method for the C-H functionalization of carbamate-protected secondary amines via α-carbamyl radicals generated using photoredox catalysis. The use of the highly oxidizing, organic acridinium photoredox catalyst
with up to three contiguous all-substituted stereocenters, are generated in high yield (up to >98%) and excellent site- regio- and diastereocontrol (>20 : 1). The use of visible light (405 or 465 nm) ensures enhanced performances by switching off undesired photodimerisation side reactions. The reaction can be easily implemented using a microfluidic photoreactor with improved productivity (up to 0.176
通过温和的可见光Paternò–Büchi工艺,由简单的吲哚和芳族酮合成了各种高度官能化的含N多环(35个实例)。具有最多三个连续的全取代立体中心的四氢氧代[2,3- b ]吲哚支架以高收率(最高> 98%)和出色的位域和非对映异构控制(> 20:1)生成。可见光(405或465 nm)的使用可通过关闭不需要的光二聚化副反应来确保增强的性能。使用微流体光反应器可以轻松地进行反应,并提高生产率(高达0.176 mmol h -1)和一般性。机理研究表明,两种替代反应机制可以解释观察到的优异的区域和非对映异构控制。
Preparation of 1-Substituted Tetrahydro-β-carbolines by Lithiation–Substitution
作者:Edward J. Cochrane、Lorraine A. Hassall、Iain Coldham
DOI:10.1021/acs.joc.5b00725
日期:2015.6.5
A method to prepare 1-substituted N-Boc-tetrahydro-beta-carbolines was developed by lithiation followed by electrophilic substitution. The deprotonation to give the organolithium was optimized by in situ IR spectroscopy and showed that the Bot group rotates slowly at low temperature. The chemistry was applied to the synthesis of 9-methyleleagnine (N-methyltetrahydroharman) and 11-methylharmicine.