title: Direct Synthesis of Protoberberine Alkaloids by Rh-Catalyzed C-H Bond Activation as the Key Step.
abstract: A one-pot reaction of substituted benzaldehydes with alkyne-amines by a Rh-catalyzed C-H activation and annulation to afford various natural and unnatural protoberberine alkaloids is reported. This reaction provides a convenient route for the generation of a compound library of protoberberine salts, which recently have attracted great attention because of their diverse biological activities. In addition, pyridinium salt derivatives can also be formed in good yields from α,β-unsaturated aldehydes and amino-alkynes. This reaction proceeds with excellent regioselectivity and good functional group compatibility under mild reaction conditions by using O2 as the oxidant.
authors.affiliation: Department of Chemistry, National Tsing Hua University, Hsinchu, 30013, Taiwan), Fax.
authors.forename: Jayachandran
authors.initials: J
authors.lastname: Jayakumar
authors.affiliation: Department of Chemistry, National Tsing Hua University, Hsinchu, 30013, Taiwan), Fax. chcheng@mx.nthu.edu.tw.
authors.forename: Chien-Hong
authors.initials: CH
authors.lastname: Cheng
mesh_terms: D000447:Aldehydes / Q000737:chemistry; D000470:Alkaloids / Q000737:chemistry*; D000480:Alkynes / Q000737:chemistry; D001547:Benzaldehydes / Q000737:chemistry; D001600:Berberine Alkaloids / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D006860:Hydrogen Bonding; D015394:Molecular Structure; D016877:Oxidants / Q000737:chemistry*
chemical_list: D000447:Aldehydes; D000470:Alkaloids; D000480:Alkynes; D001547:Benzaldehydes; D001600:Berberine Alkaloids; D016877:Oxidants; C009090:protoberberine
keywords: C−H activation; aldehydes; alkaloids; copper; rhodium