title: A fast assembly of pentacyclic benz[f]indolo[2,3-a]quinolizidine core by tandem intermolecular formal aza-[3 + 3] cycloaddition/Pictet-Spengler cyclization: a formal synthesis of (+/-)-tangutorine.
abstract: We have described a concise construction of the pentacyclic benz[f]indolo[2,3-a]quinolizidine intermediate 3 (with an overall yield of 54% for three steps), featuring a tandem intermolecular formal aza-[3 + 3] cycloaddition/Pictet-Spengler cyclization. The present work can be considered as a formal synthesis of beta-carboline alkaloid (+/-)-tangutorine. Our strategy disclosed herein constitutes a new effective general synthetic approach toward the indoloquinolizidine family of alkaloids.
authors.affiliation: Laboratory of Modern Synthetic Organic Chemistry and State Key Laboratory of Bio-Organic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China 200032.
authors.forename: Shengjun
authors.initials: S
authors.lastname: Luo
authors.forename: Jingrui
authors.initials: J
authors.lastname: Zhao
authors.forename: Hongbin
authors.initials: H
authors.lastname: Zhai
mesh_terms: D002243:Carbolines / Q000138:chemical synthesis*; D003500:Cyclization; D015394:Molecular Structure; D011807:Quinolizines / Q000138:chemical synthesis*
chemical_list: D002243:Carbolines; D011807:Quinolizines; C485396:tangutorine