A Unified Continuous Flow Assembly-Line Synthesis of Highly Substituted Pyrazoles and Pyrazolines
Author(s)
Britton, Joshua; Jamison, Timothy F
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A rapid and modular continuous flow synthesis of highly functionalized fluorinated pyrazoles and pyrazolines has been developed. Flowing fluorinated amines through sequential reactor coils mediates diazoalkane formation and [3+2] cycloaddition to generate more than 30 azoles in a telescoped fashion. Pyrazole cores are then sequentially modified through additional reactor modules performing N‐alkylation and arylation, deprotection, and amidation to install broad molecular diversity in short order. Continuous flow synthesis enables the safe handling of diazoalkanes at elevated temperatures, and the use of aryl alkyne dipolarphiles under catalyst‐free conditions. This assembly‐line synthesis provides a flexible approach for the synthesis of agrochemicals and pharmaceuticals, as demonstrated by a four‐step, telescoped synthesis of measles therapeutic, AS‐136A, in a total residence time of 31.7 min (1.76 g h⁻¹). Keywords: active pharmaceutical ingredients; agrochemicals; assembly line synthesis; multi-step continuous flow synthesis; pyrazoles
Date issued
2017-07Department
Massachusetts Institute of Technology. Department of ChemistryJournal
Angewandte Chemie International Edition
Publisher
Wiley Blackwell
Citation
Britton, Joshua and Timothy F. Jamison. “A Unified Continuous Flow Assembly-Line Synthesis of Highly Substituted Pyrazoles and Pyrazolines.” Angewandte Chemie International Edition 56, 30 (June 2017): 8823–8827 © 2017 Wiley‐VCH Verlag GmbH & Co
Version: Author's final manuscript
ISSN
1433-7851
1521-3773