Efficient Michael Addition Reactions of the N-Arylsulfonyl-3-phenylthiopiperidones. Synthesis of 3-Substituted Dihydropyrodinnes
摘要:
Efficient methods for the Michael addition reactions of N-arylsulfonyl-3-phenylthiopiperidones (1) with both the protected amidoacrylates (4, 9) and the simple acrylates (12) have been developed. These reactions offer an efficient route to the 3-alkyl-substituted dihydropyridinones (3, 11), the dienophiles employed in the natural product synthesis.
A construction of the central tetracyclic core (19) of manzamine A (1) was successfully achieved by a highly efficient Diels-Alder reaction of the suitably protected dihydropyridinones (5) and Danishefsky's diene as a key strategy. Expedient conversion of the D-A product (7) to the precursor (15) was followed by the azocine lactam ring closure to furnish the titled core.