A carboxamide can be produced in a high yield by a method for producing a carboxamide, for example, represented by formula (4):
(wherein R
1
and R
3
are as defined below), the method comprising a step of allowing a carboxylic acid ester represented by formula (1):
(wherein R
1
represents an optionally substituented C
1
-C
20
hydrocarbon group or an optionally substituented C
3
-C
20
heterocyclic group, and R
2
represents an optionally substituented C
1
-C
20
hydrocarbon group), an amine represented by formula (2):
R
3
—NH
2
(2)
(wherein R
3
represents a hydrogen atom or an optionally substituented C
1
-C
20
hydrocarbon group), and a formamide compound represented by formula (3):
(wherein R
3
is as defined above) to react in the presence of a metal alkoxide.
Derivatization of secondary alcohols ((RRCHOH)-R-1-C-2) to benzoates has frequently employed to determine enantiomer ratios using HPLC with chiral stationary phase (CSP). However, a small difference in substituents (R-1, R-2) often results in insufficient separation. To find an alternative derivatization that detects such a small difference, picolinates (2-pyridyl-(CO2CHRR2)-R-1) possessing Me/Et, Me/vinyl, Me/acetylenic, Et/n-Pr, and n-Pr/allyl substituents were prepared and separation efficiency was compared with that of benzoates ((PhCO2CHRR2)-R-1). Eight commercially available CSPs containing carbamates or benzoates of cellulose and amylose were examined to find that retention factors (k'(1) and k'(2)) and resolution (R-s) of picolinates were greater than those of the corresponding benzoates and that good to excellent R-s values (>= 1.25) were recorded over a wide range of CSPs.