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.
Efficient Michael Addition Reactions of the N-Arylsulfonyl-3-phenylthiopiperidones. Synthesis of 3-Substituted Dihydropyrodinnes
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.
Synthesis of a tetracyclic substructure of manzamine A via the Diels-Alder reaction of dihydropyridinones
A (1) was achieved via Diels-Alderreaction of the dihydropyridinones (5, 6). Conversion of the two D-A products (7, 8) to the key tricyclic ketone (10) was conducted through a conventional pathway (Scheme III) as well as a new pathway developed (Scheme IV). For effective construction of the required azocine ring systems, modelstudies were carried out to find intramolecular amide formation by pentafluorophenyl