title: Enzyme catalysed Pictet-Spengler formation of chiral 1,1'-disubstituted- and spiro-tetrahydroisoquinolines.
abstract: The Pictet-Spengler reaction (PSR) involves the condensation and ring closure between a β-arylethylamine and a carbonyl compound. The combination of dopamine and ketones in a PSR leads to the formation of 1,1'-disubstituted tetrahydroisoquinolines (THIQs), structures that are challenging to synthesize and yet are present in a number of bioactive natural products and synthetic pharmaceuticals. Here we have discovered that norcoclaurine synthase from Thalictrum flavum (TfNCS) can catalyse the PSR between dopamine and unactivated ketones, thus facilitating the facile biocatalytic generation of 1,1'-disubstituted THIQs. Variants of TfNCS showing improved conversions have been identified and used to synthesize novel chiral 1,1'-disubstituted and spiro-THIQs. Enzyme catalysed PSRs with unactivated ketones are unprecedented, and, furthermore, there are no equivalent stereoselective chemical methods for these transformations. This discovery advances the utility of enzymes for the generation of diverse THIQs in vitro and in vivo.
authors.affiliation: Department of Biochemical Engineering, University College London, Gower Street, London WC1E 6BT, UK.
authors.forename: Benjamin R
authors.identifier: 0000-0002-0033-1120
authors.initials: BR
authors.lastname: Lichman
authors.affiliation: Department of Chemistry, University College London, Christopher Ingold Building, 20 Gordon Street, London, WC1H 0AJ, UK.
authors.forename: Jianxiong
authors.initials: J
authors.lastname: Zhao
authors.affiliation: Department of Chemistry, University College London, Christopher Ingold Building, 20 Gordon Street, London, WC1H 0AJ, UK.
authors.forename: Helen C
authors.initials: HC
authors.lastname: Hailes
authors.affiliation: Department of Biochemical Engineering, University College London, Gower Street, London WC1E 6BT, UK.
authors.forename: John M
authors.initials: JM
authors.lastname: Ward