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3rd February 2014 @ 00:02

Conclusion: This is a messy and ineffective synthesis. No amide was isolated. See Preparation of 6-chloro-N-(3-chlorophenyl)pyrazine-2-carboxamide with T3P (TM 1-2) for the currently used pathway.

Reaction TM-1-1

 

A test amide coupling, to look into the effectiveness of using thionyl chloride for future amide couplings of Series 4 compounds. Depending on yields, this method may be used for future amide condensations, or may be replaced (T3P has already been suggested)

Planned synthesis:

Drawing on this paper (open access) for the synthesis: Thionyl chloride (560 mg, 4.73 mmol, 1.5 eq) and 6-chloropyrazine-2-carboxylic acid (500 mg, 3.15 mmol, 1 eq) were added to dry toluene (2.0 mL), and refluxed for 1 hour. SOCl2 removed by repeated evaporation with dry toluene. Crude acyl chloride dissolved in dry acetone (4 mL), and added dropwise to stirred m-chloroaniline (402 mg, 3.15 mmol, 1 eq) and dry pyridine (4 mL) dissolved in dry acetone (4 mL) at RT. Stirred for 30 minutes after competing addition.

In reality, the thionyl chloride proved difficult to remove, and left a brown oil. Addition of the aniline did not seem to give a reaction, and the process was ultimately abandoned in favour of the T3P-coupled scheme Preparation of 6-chloro-N-(3-chlorophenyl)pyrazine-2-carboxamide with T3P (TM 1-2)

 

HIRAC 02.03.pdf

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reaction 1-1.png
HIRAC 02.03.pdf
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