从苯胺的衍生物合成吲哚虽不常用，但还是有一些方法被报道。

一、 苯胺经傅克酰基化再还原关环合成吲哚

To a stirred solution of boron trichloride (645 mg, 5.5mmol) in drybenzene (6 mL), a solution of 4-chloroaniline 1 (638mg, 5 mmol) in dry benzene (6 mL) was added dropwise underice-cooling. To the resulting mixture containing 4-chloroanilineborontrichloride complex, chloroacetonitrile (0.38 mL, 6 mmol) and aluminumtrichloride (734 mg, 5.5 mmol) were added successively. The mixture was thenrefluxed for 6 h under nitrogen, becoming a solution of two layers. The evolvedhydrogen chloride was absorbed through a drying tube containing silica gel orcalcium chloride to a surface of aqueous sodium hydroxide. After cooling, ice 2N hydrochloric acid was added and a yellow precipitate was formed. To hydrolyzethe ketimine of 2 the mixturewas warmed at 80 °Cunder stirring, until the precipitate had dissolved (ca. 30 min). The cooledmixture was extracted with chloromethane (three times) and the organic layerwas washed with water, dried (MgS04), and concentrated. The neutralfraction obtained (744 mg) was recrystallized to obtain pure 2 (674 mg). Yield: 66%. The acidiclayer was made alkaline with 2 N sodium hydroxide and extracted withdichloromethane. Washing, drying, and evaporation of the solvent gave the basicfraction (170 mg). Thin-layer chromatographic purification (silica gel,chloroform containing 10% methanol) gave recovered 1 (103 mg).

To a stirred solution of 5-chloro-2-amino-α-chloroacetophenone2 (204 mg, l mmol) indioxane (5 mL) containing water(0.5 mL) was added sodium borohydride (1.1 mmol) and the solution was refluxedfor 5.5 h. After removal of the solvent, water was added and the mixture wasextracted with dichloromethane. The extract was dissolved in benzene and passedthrough a silica gel layer (ca. 2 g)to remove a polar fraction. The eluate with benzene was concentrated givingindole 3 (one spot, on TLC,dichloromethane). Yield: 69%

Ref: (a) T. Sugsawa, M. Adachi, K. Sasakura, A.Kitagawa, J. Org.Chem., 1979, 578, (b) Gonzalez, J.C. et al, Synthesis, 2002,475.

二、 Nenitzescu吲哚合成反应

Nenitzescu反应是一类比较特殊的吲哚合成方法，它的最终产物一般都是在N原子上有芳香环的化合物。对于Nenitzescu反应而言，最后一步合环反应采用不同的溶剂会得到不同的合环产物。如下的化合物4和5所示。

To a solution of (E)3-amino-but-2-enenitrile 1 (1.0 g, 12.2 mmol) in acetic acid (1.54 g, 25 mmol) and water (5 mL) wasadded aniline 2 (1.13 g,12.2 mol) at r.t..  After stirring for 30min., the mixture was cooled in an ice bath and the product 3 was collected on a filter, dried invacuum.  (The mixture also can beextracted with acetic ether if there was no precipitate appearance.)

To the solution of 1,4-benzo quinone (0.96 g, 9.0 mmol) in acetic acid (4 mL)was added acetic anhydride (0.8 mL) at r.t.. After stirring for 30 min., a solution of(E)3-Phenylamino-but-2-enenitrile 3 (1.18 g,7.5 mmol) in acetic acid (4 mL) was added to it and the mixture was stirredovernight.  Crude solid was collectedafter filtered, washed with a little acetic acid and water, dried invacuum.  The solid was purified by columnchromatography on silica gel using EtOAc/petro ether (1:2) as eluent to yield 6-hydroxy-3-cynao-2-methyl-1-phenyl-indole 4. (30%)

Ref: (a) R. K. Brown, The Chemistry of HeterocyclicCompounds, (b) W. J. Houlihan, Ed., 1972, 413, (c) G. R. Allen, Jr.,Org. React. 1973, 337, (d) Synthetic applications: U.Kuecklander, W. Huehnermann, Arch. Pharm. 1979, 515, (e) J. L. Bernier, J. P.,Henichart, J. Org. Chem. 1981, 4197, (f) M. Kinugawa et al.,J. Chem. Soc. Perkin Trans. I, 1995, 2677; (g) J. M. Pawlak et al., J.Org. Chem. 1996, 9055.

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