Rapid Access to 2,2-Disubstituted Indolines via Dearomative Indolic-Claisen Rearrangement: Concise, Enantioselective Total Synthesis of (+)-Hinckdentine A.

The construction of 2,2-disubstituted indolines has long presented a synthetic challenge without any general solutions. Herein, we report a robust protocol for the dearomative Meerwein-Eschenmoser-Claisen rearrangement of 3-indolyl alcohols that provides efficient access to 2-substituted and 2,2-disubstituted indolines. These versatile subunits are useful for natural product synthesis and medicinal chemistry.

Diels-Alder Reactions of 1-Alkoxy-1-amino-1,3-butadienes: Direct Synthesis of 6-Substituted and 6,6-Disubstituted 2-Cyclohexenones and 6-Substituted 5,6-Dihydropyran-2-ones.

We report the cycloaddition reactions of 1-alkoxy-1-amino-1,3-butadienes. These doubly activated dienes are prepared on a multigram scale from crotonic acid chloride and its derivatives. The dienes undergo Diels-Alder (DA) and hetero-Diels-Alder (HDA) reactions under mild reaction conditions with a variety of electron-deficient dienophiles to afford cycloadducts in good yields with excellent regioselectivities.