Cascade C-H Annulation of Aldoximes with Alkynes Using O2 as the Sole Oxidant: One-Pot Access to Multisubstituted Protoberberine Skeletons.

A cascade double C-H annulation of aldoximes with alkynes to produce benz[a]acridizinium salts is developed by using a simple catalytic system of [Cp*Rh(OAc)2]2 in the presence of Zn(OTf)2 with oxygen as the sole oxidant. In addition, the challenging C-H annulation of aldoximes with alkynes, especially arylalkynes, to synthesize 1H-isoquinolines is also achieved under slightly modified conditions. This protocol provides an efficient one-pot access to multisubstituted dehydroberberinium skeletons from simple starting materials, which can be easily transformed into berberinium and tetrahydroberberine skeletons by controlled hydrogenation.

Citation

Junbin Tang, Shiqing Li, Zheng Liu, Yinsong Zhao, Zhijie She, Vilas D Kadam, Ge Gao, Jingbo Lan, Jingsong You. Cascade C-H Annulation of Aldoximes with Alkynes Using O2 as the Sole Oxidant: One-Pot Access to Multisubstituted Protoberberine Skeletons. Organic letters. 2017 Feb 03;19(3):604-607

PMID: 28102681

search → result