Gold Catalyzed Functionalization Of Alkynes And Allenamides

An, Juzeng (2020) Gold Catalyzed Functionalization Of Alkynes And Allenamides, [Dissertation thesis], Alma Mater Studiorum Università di Bologna. Dottorato di ricerca in Chimica, 32 Ciclo.
Documenti full-text disponibili:
[img] Documento PDF (English) - Accesso riservato fino a 1 Gennaio 2023 - Richiede un lettore di PDF come Xpdf o Adobe Acrobat Reader
Disponibile con Licenza: Creative Commons Attribution Non-commercial No Derivatives 3.0 (CC BY-NC-ND 3.0) .
Download (16MB) | Contatta l'autore

Abstract

The gold(I)-catalyzed chemoselective dearomatization of β-naphthols is reported through a straightforward approach via [3,3]-sigmatropic rearrangement /allene-cyclyzation cascade processes. Easily accessed naphthyl-propargyl ethers and derivatives in this work are employed as starting materials. Delightfully, an array of deoramatized dyhydrofuryl -naphthalen-2(1H)-ones featured densely functional groups are obtained in high yields (up to 98%) in 10 min reaction time under extremely mild reaction conditions like reagent grade solvent and exposure to air. The potential of accessing to high enantioselectivety on the dearomatized dyhydrofuryl- naphthalen-2(1H)-ones is also approved by the good ee (65%) relying on (R)-xylyl- BINAP(AuCl)2. In addition, complete theoretical elucidation of the reaction pathway is also proposed which addresses a rationale for essential motivation such as regio- and chemoselectivity. Moreover, an efficient gold catalyzed intermolecular dearomatization of substituted β-naphthols with allenamides is presented here. PPh3AuTFA (5 mol %) approves the efficient dearomatively allylation protocol under mild conditions and exhibits high tolerance on substrates scope (24 examples) in good to excellent yield accompanied with high regioselectivity and stereoselectivity. Moreover, the synergistic catalytic system also highlight the synergistic function between the [PPh3Au]+ (π-acid) and TFA− (Lewis base). At last, a new chiral BINOL phosphoric acid silver salt is successfully synthesized and used as the chiral counter anion, which strongly promotes the enantioselectivity (up to 92%). At last but not least, crucially, SmI2 induced enantioselective formal synthesis of strychnine, a complex alkaloid and a classical target used to benchmark new synthetic methods is developed. Enantioselective dearomatising radical cyclisation on to the indole unit and further ET will then give organosamarium that is quenched diastereoselectively by the ester to deliver Strychnine in 7 steps.

Abstract
Tipologia del documento
Tesi di dottorato
Autore
An, Juzeng
Supervisore
Dottorato di ricerca
Ciclo
32
Coordinatore
Settore disciplinare
Settore concorsuale
Parole chiave
gold catalysis, dearomatization, alkyne,allenamides, naphthol
URN:NBN
Data di discussione
20 Marzo 2020
URI

Altri metadati

Gestione del documento: Visualizza la tesi

^