[摘要]：For the first time, tetracyclic compounds, namely, furo[2',3':3,4]cyclohepta[1,2-b]indoles were synthesized by recyclization of ortho-substituted aryldifurylmethanes containing tert-butyl groups at C5 positions of the furan rings. It was shown that [2-(benzoylamino)phenyl]bis(5-tert-butyl-2-furyl)methanes 12 are transformed into tetracycles 15 at room temperature under treatment with POCl3 in benzene solution containing some drops of water. The reaction proceeds via the intermediate formation of 1-benzoylamino-3-(5-tert-butyl-2-furyl)-2-(4,4-dimethyl-3-oxopentyl) indoles 14 which can be isolated from the reaction mixture. The method is very simple but its application is restricted due to side reactions if electron-releasing groups are present in 12. On the other hand, the decrease of electron density on furan ring in the starting compounds (for example, the use of [2-X-phenyl]difurylmethanes (where X = tosylamino or hydroxy group) prevents cyclization under the studied reaction conditions. As a result, corresponding ketones are formed as products of recyclization.
