Synthesis 2017; 49(11): 2555-2561
DOI: 10.1055/s-0036-1588148
paper
© Georg Thieme Verlag Stuttgart · New York

Sonication and Microwave-Assisted Primary Amination of Potassium­ Aryltrifluoroborates and Phenylboronic Acids under Metal-Free Conditions

Dale Kuika, J. Adam McCubbinb, c, Geoffrey K. Tranmer*a, c
  • aCollege of Pharmacy, University of Manitoba, 750 McDermot Ave., Winnipeg, Manitoba, R3E 0T5, Canada
  • bDepartment of Chemistry, University of Winnipeg, 599 Portage Ave., Winnipeg, Manitoba, R3B 2E9, Canada
  • cDepartment of Chemistry, University of Manitoba, 360 Parker Building, Winnipeg, Manitoba, R3T 2N2, Canada   Email: geoffrey.tranmer@umanitoba.ca
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Publication History

Received: 13 December 2016

Accepted after revision: 27 January 2017

Publication Date:
22 February 2017 (eFirst)

Abstract

The transition-metal-free generation of a series of primary arylamines from potassium aryltrifluoroborates and phenylboronic acids­ is reported. The method uses a mild, inexpensive source of nitrogen (hydroxylamine-O-sulfonic acid) in cooperation with aqueous sodium hydroxide in acetonitrile. Both a sonication and a microwave-assisted method were developed, which are capable of converting ArBF3K functionalities into primary arylamines (ArNH2) in isolated yields of up to 78% (10 examples for each method). This report represents the first general method for the conversion of aryltrifluoroborates into primary arylamines under mild, transition-metal-free conditions in moderate to very good yields. The method is applicable to a wide array of substrates containing electron-donating, electron-neutral, or electron-withdrawing substituents. Both the sonication and microwave methods were also applied to the generation of anilines from phenylboronic acids in isolated yields of up to 96% (12 examples for each method) that were superior to existing room temperature methods in terms of yield, while also offering much shorter reaction times (15 min vs 16 h). In particular, the microwave method is the first to allow for the conversion of arylboronic acids containing strongly electron-withdrawing substituents into the corresponding anilines in good yields, along with electron-donating­ substituents in very good to excellent yields.

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