由羰基化合物、氰化钾(KCN)和碳酸铵[(NH4)2CO3]或者氰醇和碳酸铵制备乙内酰脲的反应被称为Bucherer–Bergs反应。

七、芳胺在常见的上Boc条件，TEA/DMAP条件下通常会生成二芳基脲，有时甚至没有Boc保护产物，主要产物为二芳基脲。

八 、【 Labnetwork 】脲合成方法小结

通过硫脲合成脲

有时候我们也会通过各种氧化方法由硫脲合成脲，如双氧水，NaIO 4 ，HgO，乙酸汞，氯乙酸等。

实例：由硫脲合成脲

Sulfonythiourea(470 mg, 1 mmol) was dissolved in 1 N NaOH (3 mL) and hydrogen peroxide (0.6 mL, 30%) was added. After 1 h stirring at room temperature the mixture was acidified with 2 N HCl and the precipitate filtered off and dried to give thetile compound (420 mg, 92% yield) as colorless solid.

【Heinrich C. Englertetc J. Med. Chem. 2001, 44, 1085-1098】

1,3-二烷基硫脲在醋酸汞作用下生成1,3-二烷基-O-乙酰基异硫脲中间体，然后生成1,3-二烷基脲。

【 J. Org. Chem. , 2005, 70, 6362】

通过直接加热或铜催化对伯胺进行转酰胺基合成脲

在有些情况下，我们也会通过伯脲与胺在加热下进行胺交换来合成需要的脲。当然有时也可利用铜催化对伯胺进行转酰胺基合成脲，能有效地提高反应的收率。

实例一：通过伯脲与胺反应合成脲

The primary amide species (2 mmol) was added to an oven-dried Radleys carousel tube followed by toluene (2 mL) and the amine species (2 mmol). Hydroxylamine hydrochloride was then added and the carousel tube was sealed before the reaction mixture was heated at 105 o C. After being allowed to cool to room temperature, the solvent was removed in vacuo on a rotary evaporator and 20 mL dichloromethane added. The reaction mixture was then washed with water (2 x 30 mL) to remove the hydroxylamine hydrochloride, and the resulting organic layer was dried over MgSO 4 . The solution was concentrated in vacuo to give product.

【C. Liana Allen,* Benjamin N. Atkinson, Angewandte Chemie, International Edition , 2012, 51(6), 1383-1386】

实例二：铜催化合成脲

Cu(OAc) 2 (18 mg, 0.1 mmol), 1(135 mg, 1 mmol), aniline (121 mg, 1.3 mmol), and tert-amyl alcohol (2 mL) were added successively to a Schlenk tube (25 mL) equipped with a magnetic stirrerbar. The Schlenk tube was then closed and the resulting mixture was stirred at 140 o C for 14 h under an argon atmosphere. The accumulated ammonia gas in the pressure tube was then released under argon protection, and the reaction mixture was stirred at 140 o C for another 2 h. After cooling down to room temperature, the reaction solvent was removed under vacuum. The residue was directly purified by flash chromatography on silica gel eluting with heptane/ethanol (25:1) to give the desired compound as a white solid (165mg, 78% yield).

转自：公众号“Labnetwork”

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