Triethylborane (TEB) was found to be a mild, efficient, and acid catalyst in electrophilic substitution reaction of indoles with aldehydes compounds to afford the corresponding bis(indolyl)methanes. Vibrindole A (5) and bis(indolyl)methanes derivatives 16 and 18 were synthesized using this methodology. Compound 16 is an intermediary in the synthesis of the natural bisindoles arsindoline B (2) and streptindole (6). The structure of vibrindole A (5) was unequivocally confirmed by a single crystal X-ray diffraction analysis.

中文翻译：

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三乙基硼烷催化合成双(吲哚基)甲烷

在吲哚与醛类化合物的亲电取代反应中，三乙基硼烷 (TEB) 被发现是一种温和、高效的酸性催化剂，可提供相应的双（吲哚基）甲烷。Vibrindole A (5) 和双（吲哚基）甲烷衍生物 16 和 18 是使用这种方法合成的。化合物 16 是合成天然双吲哚arsindoline B (2) 和streptindole (6) 的中间体。通过单晶 X 射线衍射分析明确证实了 vibrindole A (5) 的结构。