Catalytic Intermolecular Hetero-Dehydro-Diels–Alder Cycloadditions: Regio- and Diasteroselective Synthesis of 5,6-Dihydropyridin-2-ones

Abstract

A novel catalyzed intermolecular hetero-dehydro-Diels-Alder reaction between push-pull 1,3-dien-5-ynes and aldimines or silylaldimines is reported. The sequence is promoted both by gold(I) or silver(I) catalysts and leads to the diastereo-and regioselective formation of 5,6-dihydropyridin-2-ones.The field of metal-catalysis (together with bio-, and organo-catalysis, one of the three feet of the vital catalytic tripod in the current scenario of organic synthesis) has achieved considerable improvement over the last decade.1 † Dedicated to Professor Rafael Suau, in memoriam.(1) For selected recent reviews on catalysis: (a) Grondal, C.; Jeanty, M.; Enders, D. Nature Chem.

Recent Progress in Dehydro(genative) Diels–Alder Reaction

“…Fernµndez-García et al reported an ovel gold-catalyzed intermolecular [4+ +2] cycloaddition between dienynes and aldimines or silylaldimines (Scheme 14). [17] This aza-DDAr eaction provided diastereo-a nd regioselective accesst o5 ,6-dihydropyridin-2-ones.I nterestingly,t he methoxysubstituted alkynyl carbon behaved in this case as am asked carbonyls urrogate. The electronic nature of the conjugated system (a push-pull system)i sc rucial to the successo ft his intermolecular DDA reaction.…”

Gold‐Catalyzed Intermolecular [4+2] and [2+2+2] Cycloadditions of Ynamides with Alkenes

“…In conclusion, prior to this study there were very few examples of gold‐catalyzed intermolecular reactions of alkynes with alkenes 1. 4, 5 This study describes gold‐catalyzed [4+2] cycloadditions of 1‐amino‐2‐aryl‐1‐ynes with alkenes 15. The reaction has a wide scope and can accommodate various alkenes, as well as ynamides which are substituted with different aryl groups.…”

1,3-Dien-5-ynes: Versatile Building Blocks for the Synthesis of Carbo- and Heterocycles

“…211 On one hand, N-substituted 5,6-dihydropyridin-2-ones are synthesized in moderate yields and in a regio-and diastereoselective manner by mixing push-pull 1,3-dien-5-ynes with aldimines under the same reaction conditions employed in their reaction with nitriles (Scheme 106, eq. 1).…”