Hydrogen Bonded Phenol‐Quinolines with Highly Controlled Proton‐Transfer Coordinate. Issue 20 (19th June 2016)

• Record Type: Journal Article
• Authors: Parada, Giovanny A.; Glover, Starla D.; Orthaber, Andreas; Hammarström, Leif; Ott, Sascha
• Is Part Of: European journal of organic chemistry. Issue 20(2016)
• Page Start: 3365
• Page End: 3372
• Publication Date: 2016-06-19
• Subjects: Hydrogen bonds -- Donor–acceptor distance -- Conjugation -- Nitrogen heterocycles -- Phenols; Chemistry, Organic -- Periodicals; Organic compounds -- Synthesis -- Periodicals; Bioorganic chemistry -- Periodicals; Chemistry, Physical organic -- Periodicals; 547
• DOI: 10.1002/ejoc.201600460
• Languages: English
• ISSNs: 1434-193X

Abstract

Abstract : A series of polycyclic phenols with intramolecular hydrogen bonds (IMHB) to quinolines was synthesized by Friedländer annulation of cycloalkanone‐functionalized anisoles with 2‐aminobenzaldehyde. The prepared compounds represent the first series of IMHB phenols in which the substitution and conjugation patterns between the phenols and the hydrogen bond acceptors are kept constant, and in which comparable electronic interaction between the two subunits is thus ensured. The distance and relative orientation between the phenolic OH and the quinolone nitrogen atom is controlled by 1, 3‐cycloalkadienes of different ring sizes to which the phenol and quinoline subunits are formally annulated. 1 H δ (OH) chemical shift and X‐ray crystal structure characterization support the conclusion that the size and conformational preference of the 1, 3‐cycloalkadiene rings control the H‐bond geometry and strength. As a result, the oxygen to nitrogen distances differ by as much as 0.30 Å across the series. Abstract : Do the twist! The strength of the intramolecular hydrogen bond between the phenolic OH and the quinoline nitrogen atom in the title compounds is controlled by the conformational preference and size of 1, 3‐cycloalkadiene tethers annelated to the heterocycles.