Practical synthesis of 3-bromo-5,6-dihydropyridin-2-ones via β,γ-unsaturated α-bromo-ketene/imine cycloaddition
摘要:
An approach to 3-bromo-4-alkyl-6-aryl-5,6-dihydropyridin-2-ones and 3 -bromo-5-ethyl-6-aryl-5,6-dihydropyridin-2-ones starting from beta,gamma-unsaturated alpha-bromoketenes and imines is reported. The presence of a bromine atom on the double bond allows performing aziridination or bromine displacement with an amine. The reaction gave fused bicyclic N-allyl-aziridines or 3-amino-substituted 5,6-dihydropyridin-2-ones, depending on the substituents on the six-membered ring. (C) 2004 Published by Elsevier Ltd.
An approach to 3-bromo-4-alkyl-6-aryl-5,6-dihydropyridin-2-ones and 3 -bromo-5-ethyl-6-aryl-5,6-dihydropyridin-2-ones starting from beta,gamma-unsaturated alpha-bromoketenes and imines is reported. The presence of a bromine atom on the double bond allows performing aziridination or bromine displacement with an amine. The reaction gave fused bicyclic N-allyl-aziridines or 3-amino-substituted 5,6-dihydropyridin-2-ones, depending on the substituents on the six-membered ring. (C) 2004 Published by Elsevier Ltd.
The Cycloaddition Reaction Between α-Bromo Vinylketenes and Imines: A Combined Experimental and Theoretical Study
The unusual behaviour of α-bromo vinylketenes in the cycloadditionreactions with imines is described. This class of vinylketenes behaves as dienophiles in [2+2] reactions, but also displays an unusual diene reactivity in [4+2] reactions. Interestingly, the reactivity of α-bromo vinylketenes can be modulated via a fine tuning of the substituents. For instance, a methyl group in the β-position completely