A stereoselective, phosphoric acid-catalyzed synthesis of dihydrochromenochromenes has been developed using transient ortho-quinone methides (o-QMs). Three contiguous stereogenic centers were formed with excellent yields, partially as single diastereomers and with moderate to excellent enantioselectivity. This intramolecular hetero-Diels− Alder reaction features unactivated dienophiles and o-QM precursors tethered by a simple phenoxy linker and furnishes cycloadducts with a prominent structural motif found in many natural products. Through an appropriate choice of dienophile configuration and backbone substitution either exo-or endo-stereoisomers were formed selectively with up to a 96:04 enantiomeric ratio.

We report herein a stereocontrolled [3 + 2]-cycloheteroannulation of bis-silyl dienediolate 1 with 2-aminobenzoic acid- and 2-aminobenzamide-derived imines to furnish highly substituted pyrrolo[1,2-a]benzoxazinones 3 and pyrrolo[1,2-a]quinazolinones 4, respectively, in good overall yields. This one-pot process rapidly generates molecular complexity and comprises a Lewis acid-catalyzed, vinylogous Mannich reaction of 1 followed by an intramolecular N,O-acetal- and N,N-aminal formation, respectively, which proceeds with good to excellent stereocontrol.

A Highly Stereocontrolled, One-Pot Approach Toward Pyrrolobenzoxazinones and Pyrroloquinazolinones Through a Lewis Acid-Catalyzed [3 + 2]-CycloannulationProcess. -Stereocontrolled cycloheteroannulation of bis-silyl dienediolate (III) with aminobenzoic acid-and aminobenzamide-derived imines provides access to pyrrolobenzoxazinones and pyrroloquinazolinones in good overall yields. This one-pot process generates molecular complexity and proceeds by a Lewis acid-catalyzed, vinylogous Mannich reaction of the bis-silyl dienediolate followed by intramolecular N,O-acetal-or N,N-aminal formation, respectively, which proceeds with good to excellent stereocontrol. -(BOOMHOFF, M.; UKIS, R.; SCHNEIDER*, C.; J. Org. Chem. 80 (2015) 16, 8236-8244, http://dx.doi.org/10.