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Continuous Flow Conditions for High Temperature Formation of a Benzodioxan Pharmaceutical Intermediate: Rapid Scaleup for Early Phase Material Delivery

By Li, Pengbin; Yang, Shaohui; Zhu, Ruiheng; Sun, Baoquan; Li, Zhongbo; Huang, Ping; Buser, Jonas Y.; Minguez, Jose Miguel; Ryan, Sarah J.

Published on

Abstract

We have developed a continuous flow method to enable rapid scaleup of an enantioenriched benzodioxan intermediate. We propose that the reaction proceeds through an intramolecular SNAr cyclization. Interestingly, traditional SNAr conditions resulted in impurity formation. When the starting material 2 was treated with alkali base in polar aprotic solvents, an undesired product regioisomer was observed. The formation of this regioisomer impurity could be suppressed by using a less polar solvent, an organic base, and high temperature. By employing continuous flow technology, these high temperature conditions could be scaled up to produce 540 g of the desired intermediate. The continuous flow reactor allowed for rapid thermal equilibration, which minimized problematic product decomposition by reducing the time that the product was exposed to high temperature.

Journal

Organic Process Research & Development. Volume 24, 2020, 1938-1947

DOI

10.1021/acs.oprd.9b00499

Type of publication

Peer-reviewed journal

Affiliations

  • Shanghai SynTheAll Pharmaceutical Co., Ltd. (“STA”)
  • Eli Lilly and Company

Article Classification

Research Article

Classification Areas

  • Intermediate

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