2-(o-Amidophenyl)oxa- and -thiazolines undergo excited-state intramolecular proton transfer (ESIPT), generating aza-o-xylylenes capable of intramolecular [4+2] and [4+4] cycloadditions with tethered unsaturated pendants. Facile hydrolysis of the primary photoproducts, spiro-oxazolidines and thiazolidines, under mild conditions unmasks a phenone functionality. Variations in linkers allow for access to diverse core scaffolds in the primary photoproducts, rendering the approach compatible with the philosophy of diversity-oriented synthesis. Chiral oxazolines, readily available from the corresponding amino alcohols, yield enantioenriched keto-polyheterocycles of complex topologies with enantiomeric excess values up to 90%.
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| http://dx.doi.org/10.1021/jacs.5b12690 | DOI Listing |
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