Functional hydrogen bonding in phloroglucinol-derived architectures

I&EC 19

Ronald K. Castellano, castellano@chem.ufl.edu, Yan Li, Andrew J. Lampkins, Edwin A. Homan, and Khalil A. Abboud. Department of Chemistry, University of Florida, P.O. Box 117200, Gainesville, FL 32611-7200
Persubstituted phloroglucinols (i.e., derived from 1,3,5-trihydroxybenzene) are the centerpiece of two classes of functional molecules that will be discussed. In one, the C3-symmetrically disposed hydroxyl groups act as hydrogen bond donors to acceptor functionalities stationed in the 2,4,6-positions of the aromatic core. Six- or seven-membered ring H-bonding then stabilizes two limiting substituent conformations (anti and syn), of which the syn offers convergent recognition groups and a cup-like shape suitable for host—guest chemistry or cage construction. H-bonding and conformational aspects describing the scaffolds are probed by 1H NMR (in solution), X-ray crystallography, and molecular modeling. Cyclization of selected phloroglucinols with hexamethylenetetramine affords a second class of functional molecules, 1-aza-adamantanetriones. Similar intramolecular H-bonding both stabilizes a propeller-shaped conformation and facilitates self-assembly of the now donor-σ-acceptor molecules. Recent data concerning the unique electronic properties of these systems will be reported.