879216-16-7Relevant academic research and scientific papers
An Enolate-Structure-Enabled Anionic Cascade Cyclization Reaction: Easy Access to Complex Scaffolds with Contiguous Six-, Five-, and Four-Membered Rings
Buk?naitien?, Rita,Javorskis, Tomas,Jurys, Arminas,Karpavi?ien?, Ieva,Orentas, Edvinas,Snarskis, Gustautas
, p. 20120 - 20128 (2020)
Catalyst-free addition of ketone enolate to non-activated multiple C?C bonds involves non-complementary reaction partners and typically requires super-basic conditions. On the other hand, highly aggregated or solvated enolates are not reactive enough to undergo direct addition to alkenes or alkynes. Herein, we report a new anionic cascade reaction for one-step assembly of intriguing molecular scaffolds possessing contiguous six-, five-, and four-membered rings, representing a formal [2+2] enol–allene cycloaddition. Reaction proceeds under very mild conditions and with excellent diastereoselectivity. Deeper mechanistic and computational studies revealed unusually slow proton transfer phenomenon in cyclic ketone intermediate and explained peculiar stereochemical outcome.
Construction of 2,3-quaternary fused indolines from alkynyl tethered oximes and diaryliodonium salts through a cascade strategy of N-arylation/cycloaddition/[3,3]-rearrangement
Ma, Xiao-Pan,Li, Kun,Wu, Si-Yi,Liang, Cui,Su, Gui-Fa,Mo, Dong-Liang
supporting information, p. 5761 - 5766 (2017/12/26)
A variety of 2,3-quaternary fused indolines could be prepared in good yields with high diastereoselectivity from alkynyl tethered oximes and diaryliodonium salts under mild metal-free conditions. The reaction initially goes through a selective N-arylation to provide alkynyl tethered nitrones and regioselectively undergoes an intramolecular (3 + 2) cycloaddition followed by a [3,3]-sigmatropic rearrangement to afford 2,3-quaternary fused indolines in a one-pot fashion. The method features easily available cheap materials, multiple bond formation, gram scalable preparation and diversity of fused indoline scaffolds.
