The reverse Cope cyclisation: a classical reaction goes backwards

Total Synthesis of the Lycorenine-Type Amaryllidaceae Alkaloid (±)-Clivonine via a Biomimetic Ring-Switch from a Lycorine-Type Progenitor

“…The synthesis of (±)-clivonine progenitor 15 parallels our previous synthesis of (+)-trianthine (16), employing a retro-Cope elimination 17 (11 → 12) as the key step (Scheme 2). Prior studies in which we had been unable to obtain lactamol 17 cleanly, via lactam half-reduction Scheme 3.…”

Intermolecular Cope‐Type Hydroamination of Alkenes and Alkynes

“…[4] A conceptually different approach to the functionalization of alkenes and alkynes in intramolecular reactions is the Cope-type hydroamination (also referred to as reverse-Cope cyclization). [5,6] While this strategy has received some attention (particularly in the formation of five-and six-membered heterocycles), fundamental limitations have precluded its application in synthesis and in more challenging intermolecular reactions. Notably, the nitrogen atom is usually substituted to increase reactivity, but this severely limits the reaction scope, leading to the formation of amine oxides, which are less versatile synthetic intermediates and less stable products.…”

Diastereo‐Divergent Synthesis of Saturated Azaheterocycles Enabled by tBuOK‐Mediated Hydroamination of Alkenyl Hydrazones

“…[1,2] As one of the moste fficientw ayst oc onstruct saturated azaheterocycles, an intramolecular hydroamination of alkenyl amines and their derivatives has been intensively studiedusing various metal complexes (alkali/transition metals and f-block elements) and Brønsted acids. [3,4] The diastereoselectivity in these cyclization processes is remarkably affected by the substituents on the nitrogen atom and the targeted ring size. [3] In the formation of pyrrolidines from g,d-unsaturated amines, hydroamination with primary amines commonlye xhibits 2,5-trans selectivity, [5] whereas secondary amines deliver 2,5-cis products in general (Scheme 1a).…”