Brønsted Base‐Catalyzed Umpolung Intramolecular Cyclization of Alkynyl Imines

• Published in: Chemistry : a European journal Vol. 24; no. 16; pp. 3998 - 4001
• Main Authors: Kondoh, Azusa, Terada, Masahiro
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 15.03.2018; Wiley Subscription Services, Inc
• Subjects: Alkynes; Brønsted base catalysis; Carbon; Catalysis; Chemistry; Chemistry, Multidisciplinary; Imines; intramolecular cyclization; Nitrogen; organocatalysts; Physical Sciences; rearrangement; Science & Technology; umpolung; 1,2-DIHYDROISOQUINOLINES; umpolung; ALDEHYDES; organocatalysts; 2-ALKYNYLBENZALDEHYDES; PHOSPHA-BROOK REARRANGEMENT; ACYL ANION EQUIVALENTS; PHOSPHONATES; Bronsted base catalysis; intramolecular cyclization; ACYLPHOSPHONATES; ESTERS; TANDEM NUCLEOPHILIC-ADDITION; GENERATION; rearrangement; Brønsted base catalysis
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201800219

A novel “umpolung” intramolecular cyclization of alkynyl imines, in which the electrophilic imine sp2‐carbon formally serves as a nucleophilic site, was developed under Brønsted base catalysis. The reaction involves the unprecedented catalytic generation of α‐aminoester enolates from α‐iminoesters via the 1,2‐addition of the anion of a secondary phosphite to an imine moiety followed by the [1,2]‐rearrangement of a dialkoxyphosphoryl moiety from carbon to nitrogen, which is a formal umpolung process, and the intramolecular addition to an alkyne. This is a rare example of a [1,2]‐rearrangement of a dialkoxyphosphoryl moiety from carbon to nitrogen to generate an α‐amino carbanion and the first catalytic carbon–carbon bond forming reaction utilizing the resulting carbanion as a nucleophile. A novel “umpolung” intramolecular cyclization of alkynyl imines, in which the electrophilic imine sp2‐carbon formally serves as a nucleophilic site, was developed under Brønsted base catalysis. This is a rare example of a [1,2]‐rearrangement of a dialkoxyphosphoryl moiety from carbon to nitrogen to generate an α‐amino carbanion and the first catalytic carbon–carbon bond‐forming reaction utilizing the resulting carbanion as a nucleophile.