Zaghi Anna, Ragno Daniele, Di Carmine Graziano, De Risi Carmela, Bortolini Olga, Giovannini Pier Paolo, Fantin Giancarlo, Massi Alessandro
Dipartimento di Scienze Chimiche e Farmaceutiche, Università di Ferrara, Via Fossato di Mortara 17, I-44121 Ferrara, Italy.
Beilstein J Org Chem. 2016 Dec 13;12:2719-2730. doi: 10.3762/bjoc.12.268. eCollection 2016.
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 ,-dimethylformamide (DMF) solvent to the α-diketone and generate the corresponding enediolate active species. After having identified the 2--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).
本文介绍了一种便捷的多相连续流方法，用于实现芳香族α-二酮的极性反转。首先进行了预备性的间歇实验，以选择最佳的负载型碱，该碱能够引发从N，N-二甲基甲酰胺（DMF）溶剂的氨基甲酰阴离子到α-二酮的双电子转移过程，并生成相应的烯二醇盐活性物种。在确定聚苯乙烯负载的2-叔丁基亚氨基-2-二乙氨基-1,3-二甲基全氢-1,3,2-二氮杂磷腈（PS-BEMP）为合适的碱之后，制备并操作了填充床微反应器（耐压不锈钢柱），以高效地实现芳酰化α-羟基酮和2-苯甲酰基-1,4-二酮（分别为安息香类和施陶丁格类产物）的化学选择性合成，并且填充材料具有长期稳定性（长达五天）。
