Accelerated Hantzsch electrospray synthesis with temporal control of reaction intermediates

作者：Bain Ryan M; Pulliam Christopher J; Cooks R Graham^*

来源：Chemical Science, 2015, 6(1): 397-401.

DOI：10.1039/c4sc02436b

Complex chemical reactions can occur in electrosprayed droplets on the millisecond time scale. The Hantzsch synthesis of 1,4-dihydropyridines was studied in this way using on-line mass spectral analysis to optimize conditions and characterize the product mixture. Changing the distance between the nanospray source and the MS inlet allowed exploration of reaction progress as a function of droplet time-of-flight. Desolvation of the charged microdroplets is associated with transformation from starting material to intermediates and eventually to product as the distance is increased. Results of the on-line experiments require a termination step that discontinuously completes the desolvation process and allows the generated gaseous ions to be used to characterize the state of the system at a particular time. The intermediates seen correspond to those known to occur in the bulk solution-phase reaction. Offline collection of the sprayed reaction mixture allowed the recovery of 250 mg h(-1) of desired reaction product from a single sprayer, permitting characterization by NMR and other standard methods. A thin film version of the accelerated reaction is described and it could be controlled through the temperature of the collection surface.

• 出版日期2015