title: Isothiourea-Mediated Organocatalytic Michael Addition-Lactonization on a Surface: Modification of SAMs on Silicon Oxide Substrates.
abstract: Tailoring the functionality of self-assembled monolayers (SAMs) can be achieved either by depositing prefunctionalized molecules with the appropriate terminal groups or by chemical modification of an existing SAM in situ. The latter approach is particularly advantageous to allow for diversity of surface functionalization from a single SAM and if the incorporation of bulky groups is desired. In the present study an organocatalytic isothiourea-mediated Michael addition-lactonization process analogous to a previously reported study in solution is presented. An achiral isothiourea, 3,4-dihydro-2H-pyrimido[2,1-b]benzothiazole (DHPB), promotes the intermolecular Michael addition-lactonization of a trifluoromethylenone terminated SAM and a variety of arylacetic acids affording C(6)-trifluoromethyldihydropyranones tethered to the surface. X-ray photoelectron spectroscopy, atomic force microscopy, contact angle, and ellipsometry analysis were conducted to confirm the presence of the substituted dihydropyranone. A model study of this approach was also performed in solution to probe the reaction diastereoselectivity as it cannot be measured directly on the surface.
authors.affiliation: EaStCHEM School of Chemistry, University of St. Andrews , North Haugh, St. Andrews KY16 9ST, U.K.
authors.forename: Ross
authors.initials: R
authors.lastname: Chisholm
authors.affiliation: EaStCHEM School of Chemistry, University of St. Andrews , North Haugh, St. Andrews KY16 9ST, U.K.
authors.forename: John D
authors.initials: JD
authors.lastname: Parkin
authors.affiliation: EaStCHEM School of Chemistry, University of St. Andrews , North Haugh, St. Andrews KY16 9ST, U.K.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Smith
authors.affiliation: EaStCHEM School of Chemistry, University of St. Andrews , North Haugh, St. Andrews KY16 9ST, U.K.
authors.forename: Georg
authors.initials: G
authors.lastname: Hähner