Simple and Efficient Synthesis of 3,4-Dihydro-2-pyridones via Novel Solid-Supported Aza-Annulation

Abstract
A diverse array of 3,4-dihydro-2-pyridones 13 were produced utilizing the unique properties of solid-supported reactions to both drive the reactions to completion and isolate the desired products. The pyridones were synthesized in high purity by a simple sequence of novel steps commencing from an acetophenone-functionalized resin. The para-substituted acetophenone 9 could be anchored to the resin through either a sulfonamide or a carboxamide linkage. The sulfonamide resin 9a, which gave the best results, was treated with several aryl aldehydes and ethoxide to give a variety of chalcones 10a − k in excellent yield (82−99%) upon TFA cleavage. Addition of either methyl or allyl malonate and DBU to 10a − k afforded smoothly the Michael adducts 11a − j (70−99%) which were subsequently cyclized in one step employing acetic acid as a catalyst and several diverse amines to give pure 3,4-dihydro-2-pyridones 13a − p in moderate to excellent yields (30−98%).

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