Selective C-O Bond Forming Reactions at Indole-C2-Position toward Polycyclic Indolone or Indolinone Derivatives Tethered with Medium-Sized Rings

Authors：Wang, Zongkang; Yin, Liqiang; Wang, Mengdan; Zhu, Yilin; Yang, Yajie; Cheng, Lu; Wang, Chengyu^*; Li, Yanzhong^*

Source：Organic Letters, 2022, 24(34): 6272-6276.

DOI：10.1021/acs.orglett.2c02398

• INTRAMOLECULAR CYCLIZATION

A methodology involving the chemoselective synthesis of tetracyclic [1,3]oxazino[3,2-a]indol-4-one or tetracyclic [1,3]oxazino[3,2-a]indoline-4-one tethered with a medium-sized ring by cross dehydrogenative coupling (CDC) or nucleophilic addition (NA) reaction has been developed. [1,3]Oxazino[3,2-a]indol-4-one compounds fused with a medium-sized ring were constructed through a CDC reaction in the presence of I-2 and K2CO3. Whereas, [1,3]oxazino[3,2-a]indoline-4-ones tethered with a medium-sized ring were obtained with a TfOH system by NA reaction.