Rhodium-catalyzed oxidative annulation reactions of 3-(1H-indol-3-yl)-3-oxopropanenitriles with internal alkynes have been developed. A series of substituted carbazoles and 4H-oxepino[2,3,4,5-def]carbazoles, through a formal Rh(III)-catalyzed (4+2) cycloaddition with an alkyne and tandem (4+2) and (5+2) cycloaddition with two molecules of alkynes, were obtained. The reactions involved sequential cleavage of C(sp²)–H/C(sp³)–H bonds and annulation with an alkyne in the first step, and sequential cleavage of C(sp²)–H/O–H bonds and annulation with another alkyne in the second step. Some of the 4H-oxepino[2,3,4,5-def]carbazole products exhibit intense fluorescence in the solid state.

中文翻译：

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铑催化带有内部炔烃的3-（1 H-吲哚-3-基）-3-氧代丙烷腈的C2和C4 C–H活化/环化：容易获得取代和稠合的咔唑

已经开发了铑催化的3-（1 H-吲哚-3-基）-3-氧代丙烷腈与内部炔烃的氧化环化反应。通过带有炔烃和串联（4 + 2）的正式Rh（III）催化的（4 + 2）环加成反应，生成一系列取代的咔唑和4 H -oxepino [2,3,4,5- def ]咔唑获得5 + 2）与两个炔烃分子的环加成。反应包括第一步中的C（sp ²）–H / C（sp ³）–H键的顺序裂解和炔烃的环化，以及C（sp ²）–H / O–H键的连续裂解和环化的顺序。第二步是与另一个炔烃 4 H -oxepino [2,3,4,5- def中的一些]咔唑产品在固态时表现出强烈的荧光。