A convenient heterogeneous continuous-flow procedure for the polarity reversal of aromatic α-diketones is presented. Propaedeutic batch experiments have been initially performed to select the optimal supported base capable to initiate the two electron-transfer process from the carbamoyl anion of the N,N-dimethylformamide (DMF) solvent to the α-diketone and generate the corresponding enediolate active species. After having identified the 2-tert-butylimino-2-diethylamino-1,3-dimethylperhydro-1,3,2-diazaphosphorine on polystyrene (PS-BEMP) as the suitable base, packed-bed microreactors (pressure-resistant stainless-steel columns) have been fabricated and operated to accomplish the chemoselective synthesis of aroylated α-hydroxy ketones and 2-benzoyl-1,4-diones (benzoin- and Stetter-like products, respectively) with a good level of efficiency and with a long-term stability of the packing material (up to five days).
提出了一种方便的异质连续流程,用于芳香族α-二酮的极性反转。首先进行了初步的批量实验,以选择能够从N,N-二甲基甲酰胺(DMF)溶剂的碳酰胺负离子向α-二酮发起两电子转移过程并生成相应的烯二醇酸活性物种的最佳支持碱。在确定了聚苯乙烯(PS-BEMP)上的2-tert-丁基亚胺-2-二乙基氨基-1,3-二甲基过氧化-1,3,2-二氮磷烷作为合适的碱后,制备并操作了填充床微反应器(耐压不锈钢柱),以实现芳基化α-羟基酮和2-苯甲酰-1,4-二酮(苯甲酮和Stetter样品,分别)的化学选择性合成,效率较高,并且填料材料的长期稳定性(长达五天)。