High pressure-assisted low-loading asymmetric organocatalytic conjugate addition of nitroalkanes to chalcones
作者:Agnieszka Cholewiak、Kamil Adamczyk、Michał Kopyt、Adrian Kasztelan、Piotr Kwiatkowski
DOI:10.1039/c8ob00561c
日期:——
to 9 kbar) allows for relatively fast (1–5 h) and highly enantioselective 1,4-addition of nitromethane and 2-nitropropane to chalcones at room temperature with substantial reduction of catalyst loading (0.2–1 mol% of cinchona alkaloid-based thioureas and squaramides). Various γ-nitroketones were obtained at 9 kbar with high yield and enantioselectivity (up to 98%), whereas in control experiments at atmospheric
施加高压(最高9 kbar)可在室温下相对快速地(1-5小时)和硝基甲烷和2-硝基丙烷的对映体1,4-对映体选择性高的加成反应,同时大大降低了催化剂的负载量(0.2-1摩尔%的基于金鸡纳生物碱的硫脲和方酸酰胺)。在9 kbar下以高收率和对映选择性(高达98%)获得了各种γ-硝基酮,而在大气压下的对照实验中,通常在20 h后仅生成少量(<10%)的产物。