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20th August 2014 @ 02:08


Using similar conditions to Resynthesis of methyl 6-chloro-2-pyrazinecarboxylate (TM 5-3)Resynthesis of methyl 6-chloro-2-pyrazinecarboxylate (TM 5-3), TM 38-1 (crude: Synthesis of 3-(ethoxycarbonyl)pyrazine 1-oxide (TM 38-1), 14.2 g) was placed in thionyl chloride (50 mL), and heated to 60 oC. The initial heating caused rapid bubbling, and possibly an exotherm (bath temperature rose to 65 oC, and continued to rise for several minutes without hotplate input). After around half an hour, the reaction (observed by bubbling) slowed, and the bath temperature was raised to 90 oC. The reaction mixture was refluxed for 5 hours, then cooled to rt and left overnight. Thionyl chloride was then removed under reduced pressure (and quenched with ice water, then neutralised with NaOH), and the remaining material quenched by addition of water (~100 mL), then neutralised with Na2CO3 solution. (~150 mL). The product was extracted with DCM (5 x 100 mL), the combined organic portions washed with brine (100 mL), and concentrated under reduced pressure to give a dark red liquid. This crude material was purified by column chromatography (hexanes, EtOAc) to give TM 53-1 as a yellow liquid (9.30 g).






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Re: Synthesis of ethyl 6-chloropyrazine-2-carboxylate (TM 53-1 by Alice Williamson
30th August 2014 @ 03:18
HIRAC seen and approved.