title: 2-(methoxycarbonyl)ethyl as a removable N-protecting group: synthesis of indoloisoquinolinones by Pd(II)-catalyzed intramolecular diamination of alkynes.
abstract: Pd(II)-catalyzed double cyclization of 1,2-diarylethynes bearing an N-methyl-N-[2-(methoxycarbonyl)ethyl]amino and an aminocarbonyl group at the ortho positions of the two aromatic rings afforded the tetracyclic N-[2-(methoxycarbonyl)ethyl]indoloisoquinolinones in good to excellent yields. The N-[2-(methoxycarbonyl)ethyl] group is readily removed under basic conditions (DBU, DMF, 120 °C) to afford the corresponding tetracycles with a free indolyl nitrogen in excellent yields. The 2-(methoxycarbonyl)ethyl as a removable N-protecting group is illustrated in other Pd(II)- and Pd(0)-catalyzed and selenium-mediated transformations.
authors.affiliation: Laboratory of Synthesis and Natural Products, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, EPFL-SB-ISIC-LSPN, BCH 5304, 1015 Lausanne, Switzerland.
authors.forename: Tu M
authors.initials: TM
authors.lastname: Ha
authors.affiliation: Laboratory of Synthesis and Natural Products, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, EPFL-SB-ISIC-LSPN, BCH 5304, 1015 Lausanne, Switzerland.
authors.forename: Bo
authors.initials: B
authors.lastname: Yao
authors.affiliation: Laboratory of Synthesis and Natural Products, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, EPFL-SB-ISIC-LSPN, BCH 5304, 1015 Lausanne, Switzerland.
authors.forename: Qian
authors.initials: Q
authors.lastname: Wang
authors.affiliation: Laboratory of Synthesis and Natural Products, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne, EPFL-SB-ISIC-LSPN, BCH 5304, 1015 Lausanne, Switzerland.
authors.forename: Jieping
authors.initials: J
authors.lastname: Zhu