Continuous flow synthesis of alkynes from isoxazolones

The development of a continuous flow approach for the generation of alkynes from isoxazolones under diazotisation conditions is reported. Although the underlying transformation has been known for several decades, variable yields, excessive use of sodium nitrite, and limited scalability due to the exothermic nature and the release of copious amounts of toxic nitroxide gases have plagued its performance in batch mode. These limitations are overcome by the presented flow approach, which delivers various alkyne products with residence times of less than 1 minute and productivities of approximately 2 g h⁻¹. The value of continuous flow processing in miniaturised devices is thus demonstrated, rendering this alkyne-forming method an attractive addition to the limited synthetic toolbox for this important functional group.

• Loftus, A
• De Gregorio, R
• Baumann, M

• University College Dublin, School of Chemistry, Science Centre South, D04 N2E5 Dublin, Ireland

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