Reduction of 1. nitro
硝基的还原是一种常用的合成伯胺的方法特别是芳香伯胺，一般而言，最干净和简便的还原方法就是通过Pd/C或Raney Ni加氢，但是当分子内存在对加氢敏感的官能团如：卤素（Cl, Br and I; F 对加氢不敏感），双键，三键时，我们不得不采用化学还原的方法，最为经典的要数铁粉的还原，SnCl2还原，另外Abderahman曾报道（Synthesis，1988, 2, 154-155）应用保险粉在乙醇中加热的方法还原硝基，虽然在文献中他们使用了碱，但在实践中我们发现，只要用保险粉在乙醇中回流几小时即可。这一方法也是一个较为简便，易于处理的反应，
The reduction of nitro is a commonly used method for synthesizing primary amines, especially aromatic amines. Generally, the cleanest and simple reduction method is hydrogenation through Pd/C or Raney Ni, but when molecules are stored in hydrogen sensitive functional groups such as halogens (Cl, Br and I; F against hydrogenation), double bonds, and three keys, we do not No chemical reduction method is used, the most classical reduction of iron powder, SnCl2 reduction, and Abderahman reported (Synthesis, 1988, 2, 154-155) using the method of heating the powder in ethanol to reduce nitro, although in the literature they used alkali, but in practice, we found that as long as the powder is used in B. The alcohol can be reflued for a few hours. This method is also a simple and easy to handle reaction.
In general, nitro compounds do not have to be reduced by lithium hydride aluminum (LAH), because lithium aluminum hydride (LAH) can not reduce the nitro group thoroughly to get a mixture, but for unsaturated conjugated nitro compounds, they can be reduced by reduction of lithium aluminum hydride (LAH) or NaBH4-Lewis acid to obtain saturated amines.
Reduction of 2. amides
酰胺的还原也是合成胺基的一种常用的方法，其常常用于伯胺的单烷基化，一般将酰胺还原到胺最常见的方法就是通过LAH在加热回流下进行，但当分子内有对LAH还原敏感的官能团存在时，如芳环上有卤原子存在特别是溴和碘存在时（在此剧烈的条件下，容易造成脱卤），分子内存在其他的碳酰胺等等。因此这时需要一些温和的还原条件，目前常用的有：硼烷还原，NaBH4-Lewis 酸体系还原，DIBAL还原等等。另外碳酰胺在LAH的还原条件下，也可被还原成为甲基，这也是一个常用的将伯胺单甲基化的一种方法。一般由于Boc (叔丁氧羰基)，易于反应，及中间体的提纯，因此常用于此类反应。
The reduction of amides is also a common method for the synthesis of amine groups. It is often used for the mono alkylation of primary amine. The most common method of reducing amides to amines is through LAH in reflux reflux, but when the molecules are sensitive to LAH reduction, there are halogen atoms in the aromatic ring, especially bromine and iodide. At that time, it is easy to cause dehalogenate under these severe conditions. The molecules are stored in other carbamides and so on. Therefore, some mild reduction conditions are needed at this time. Now, commonly used are borane reduction, NaBH4-Lewis acid system reduction, DIBAL reduction and so on. In addition, carbamide can also be reduced to methyl under LAH reduction, which is also a commonly used methylation method for primary amine. The general Boc (TERT butoxycarbonyl), easy reaction, purification and intermediates, so commonly used in these reactions.
Reduction of 3. nitrile groups
一般腈基还是较为容易为相应的伯胺，催化加氢或化学试剂还原都可以用于这类还原，催化加氢的方法最为常用的催化剂为Ranney Ni, 再使用Ranney Ni 做催化剂加氢成胺，若用乙醇作溶剂时，一般需要加入氨水，主要由于在此条件下，有时有微量的乙醇会氧化为乙醛，其与产品发生还原胺化得到乙基化的产物，加入氨水或液氨可抑制该副反应。化学还原方法则以LAH 和硼烷较为多用。
The general nitrile base is relatively easy to be a corresponding primary amine. Catalytic hydrogenation or chemical reagents can all be used for this type of reduction. The most commonly used catalyst for catalytic hydrogenation is Ranney Ni, and then Ranney Ni is used as a catalyst for hydrogenation to amines. If ethanol is used as a solvent, ammonia water is usually added, mainly due to the conditions. At the same time, a small amount of ethanol will sometimes be oxidized to acetaldehyde, which is reduced to the product by the reduction amination of the product to the product of ethyl, and the addition of ammonia or liquid ammonia can inhibit the reaction. LAH and borane are widely used in chemical reduction.
Reduction of 4. azide
Azide reduction is also a commonly used method for preparing alkyl amines. Generally alkyl azides are mainly substituted for alkyl halides with azide groups, and alkyl alcohols can be converted directly to alkyl azide through DPPA (generally as primary alcohols). Although azide has been used in many documents to get alkyl azide through high yield of MItsunobu with alcohol, it is not recommended in the laboratory because of the volatility and toxicity of azido. For tertiary alcohols, it can also be converted to tertiary alkyl azide through TMSN3 in the presence of Lewis acid.
催化加氢和化学还原法均可用于叠氮的还原，常用的催化加氢催化剂为Pd/C, Raney Ni, 当分子内有对氢化敏感的卤素时，可用PtO2作催化剂。化学还原最温和的条件是使用三苯基膦在湿的四氢呋喃中还原，当然LAH也可用于该还原。
Catalytic hydrogenation and chemical reduction can be used for the reduction of azide. The commonly used catalyst for catalytic hydrogenation is Pd/C, Raney Ni. When the molecules are sensitive to hydrogenated halogens, PtO2 can be used as a catalyst. The most mild condition for chemical reduction is the reduction of three phenylphosphine in wet tetrahydrofuran, and of course, LAH can also be used for this reduction.