酰胺的脱水反应可在P2O5、POCl3、SOCl2、PCl5等脱水剂存在下进行脱水反应生成腈，此为实验室合成腈的方法之一。

N-叔丁酰胺也可当作酰胺的替代品，在二氯亚砜，三氯氧磷或草酰氯作用下脱叔丁醇制备腈，因此有时在制备酰胺不容易时，做成相应的叔丁酰胺转化为腈也不失为一个好的方法。

反应实例

A solution of 1.240 mmol ofN-tert-butyl-4-(6,7-dihydro-5H-[2]pyridin-7-yl)benzamide and 1.0 ml of thionylchloride in 30 ml of chloroform is stirred under reflux for 6 hours.  The reaction mixture is cooled to roomtemperature and evaporated.  The residueis taken up in dichloromethane and mixed with saturated aqueous sodiumbicarbonate solution.  The organic phaseis separated and the aqueous phase is extracted with dichloromethane (2x).  The combined organic phases are dried withsodium sulphate and concentrated.  Theresidue is dissolved in diethyl ether and the title compound is converted intothe hydrochloride salt by adding ethereal HCI solution (2N).  The solid is stirred in diethyl ether/acetone(1: 1), filtered and dried.  The titlecompound is obtained as a dark grey solid.  Rf (free base) = 0.36 (EtOAc)

Reference: WO2005/118540 

A 5 L round bottom flask was charged with N,N'-di-tert-butyl-5-(2,3-difluoro-6-nitro-phenoxy)-isophthalamide (21; 564 g) and 1.3 L ofphosphorus oxychloride.  The mixture washeated to between 90 deg C. ~ 100.deg. C. for 2 h, after which approximately1/2 of the POCl3was removed by distillation.  Toluene was added (1 L) and additional liquidwas distilled.  After cooling the mixtureovernight, a crude was obtained by filtration. Additional material was obtained by recovery from the mother liquid.  The combined solids were stirred in MeOH (0.7L) for between 1 and 3 h, filtered and dried in a vacuum oven between 50~80 degC.at 25 Torr with a nitrogen bleed to afford 339 g of 22 (90percent theory).

Reference: US2005/234236

At ice-water bath, oxalyl chloride (0.345 ml) wasadded dropwise to a solution of 1.0 g of ethyl1-{4-[2-(t-butylaminocarbonyl)phenyl]phenyl}methyl-4-(1-hydroxy-1-methylethyl)-2-propylimidazole-5-carboxylate in 10 ml of methylene chloride.  The mixture was stirred at the sametemperature for 2 hours.  The reactionmixture was diluted with an aqueous solution of sodium hydrogencarbonate andethyl acetate, and the ethyl acetate layer was separated, dried over anhydrousmagnesium sulfate and concentrated by evaporation under reduced pressure.  The residue was purified by silica gel columnchromatography, using 1:1 EtOAc/hex (v/v) as the eluent, to give 0.69 g of thetitle compound as crystals.

Reference: US5616599 

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