Total synthesis of carbazomycins E and F was achieved by double functionalization of an aryne intermediate generated from a 2-aminobiphenyl derivative. The tethered amino group underwent nucleophilic addition to the aryne intermediate to construct the carbazole skeleton. The resulting carbanion was formylated to give the multiply substituted carbazole. This formyl group caused several problems. For example, it was difficult to perform regioselective demethylation of the methoxy group proximal to the formyl group without protecting the carbazole nitrogen. In addition, the formyl group was unexpectedly reduced to give a methoxymethyl group under heating conditions with copper iodide and sodium methoxide. Oxidation of this compound in the presence of water was effective for obtaining the formylated carbazole, leading to the first total synthesis of carbazomycin F.

中文翻译：

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卡巴佐霉素 E 和 F 的全合成

卡佐霉素 E 和 F 的全合成是通过对 2-氨基联苯衍生物生成的芳炔中间体进行双官能化来实现的。束缚的氨基与芳基中间体进行亲核加成以构建咔唑骨架。将所得碳负离子甲酰化，得到多取代的咔唑。该甲酰基引起了几个问题。例如，在不保护咔唑氮的情况下，很难对甲酰基附近的甲氧基进行区域选择性去甲基化。此外，在加热条件下用碘化铜和甲醇钠将甲酰基意外地还原成甲氧基甲基。该化合物在水存在下的氧化可有效获得甲酰化咔唑，从而首次全合成了卡佐霉素 F。