Metallfreie oxidative Cyclisierung von Alkinyl‐Aryl‐Ethern zu Benzofuranonen

Graf, Katharina; Rühl, Carmen L.; Rudolph, Matthias; Röminger, Frank; Hashmi, A. Stephen K.

doi:10.1002/ange.201304813

Cited by 40 publications

(8 citation statements)

References 50 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Of note,H OTf could also catalyze this reaction in 16 %y ield. [12,13] In addition, the use of PhCl as the solvent at 100 8 8Cgave aslightly improved yield (entry 4). Theyield of product 2awas further increased to 61 %byusing 2,6-dibromopyridine N-oxide (3b)a st he oxidant (entry 5).…”

mentioning

confidence: 99%

Zinc‐Catalyzed Alkyne Oxidation/CH Functionalization: Highly Site‐Selective Synthesis of Versatile Isoquinolones and β‐Carbolines

et al. 2015

View full text Add to dashboard Cite

An efficient zinc(II)-catalyzed alkyne oxidation/C-H functionalization sequence was developed, thus leading to highly site-selective synthesis of a variety of isoquinolones and β-carbolines. Importantly, in contrast to the well-established gold-catalyzed intermolecular alkyne oxidation, over-oxidation can be completely suppressed in this system and the reaction most likely proceeds by a Friedel-Crafts-type pathway. Mechanistic studies and theoretical calculations are described.

show abstract

mentioning

confidence: 99%

Zinc‐Catalyzed Alkyne Oxidation/CH Functionalization: Highly Site‐Selective Synthesis of Versatile Isoquinolones and β‐Carbolines

et al. 2015

View full text Add to dashboard Cite

show abstract

“…A related precedent is the synthesis of dihydrobenzofuranones by Hashmi,10 where the stoichiometric electrophile is a proton in the form of HBF 4 etherate (Scheme B). Notably in this case, the alkynes are electron‐rich, and products do not incorporate extra functionality.…”

Section: Methodsmentioning

confidence: 99%

Polycomb Determines Responses to Smad2/3 Signaling in Embryonic Stem Cell Differentiation and in Reprogramming

Dahle

Kuehn

2013

Stem Cells

View full text Add to dashboard Cite

Integration of extrinsic signals, epigenetic regulators, and intrinsic transcription factors establishes pluripotent stem cell identity. Interplay between these components also underlies the capacity of stem cells to undergo differentiation, and of differentiated cells to re-establish the pluripotent state in direct reprogramming. Polycomb repressive complexes are epigenetic regulators that play key roles in stem cell identity and in differentiated cell fates. Smad2 and Smad3 (Smad2/3), the intracellular mediators of the Nodal/ Activin/transforming growth factor (TGF) b cell-cell signaling pathway also are implicated in stem cell pluripotency and in differentiation. Here, we show that Polycomb imposes responses to Smad2/3-mediated signaling to selectively regulate expression of the master pluripotency factor Oct4 during initiation of differentiation, but not in the selfrenewing pluripotent ground state. During reprogramming back to the ground state, we find that the enhancement of reprogramming efficiency stemming from blocking Nodal/ Activin/TGFb signaling also depends on Polycomb. These context-dependent responses to Smad2/3 imposed by Polycomb action provide a mechanism for selective gene regulation that can reconcile the apparently conflicting roles of this signaling pathway in pluripotency, differentiation, and reprogramming.

show abstract

“…Ar elated precedenti st he synthesis of dihydrobenzofuranones by Hashmi, [10] where the stoichiometric electrophile is ap roton in the form of HBF 4 etherate (Scheme 1B). Notably in this case,t he alkynes are electron-rich,a nd products do not incorporate extra functionality.…”

mentioning

confidence: 99%

Direct Conversion of Internal Alkynes into α‐Iodoenones: One‐Step Collaborative Iodination and Oxidation

Wang

Genoux

Ghorai³

et al. 2016

Adv Synth Catal

View full text Add to dashboard Cite

Ther eactiono fa ni nternal alkyne with 2,6-dichloropyridine N-oxide,anucleophilic oxidant, and electrophilic N-iodosuccinimide (NIS)s imultaneously enables the direct access to versatile a-iodoenones.E lectronically biased internala lkynes undergo the one-stept ransformation with excellent regioselectivities andw ith practical Z/E ratios.I n comparison to the relatedo xidative gold catalysis using pyridine N-oxides,t his reaction employs NIS as the stoichiometric ynophile instead of the soft acidic noble metal catalyst and affords products featuring an additional versatileC À Ib ond. Similar strategies for replacing ynophilic cationic gold(I) complexes in oxidative gold catalysis with likewise ynophilic stoichiometric electrophiles would enable the development of new synthetic methods.Keywords: alkynes;e nones; iodination;o xidation; pyridine N-oxides a-Iodoenones possess an electrophilic enone moiety susceptible to either 1,4-or 1,2-addition andaversatile C À Ib ondf or transitionm etal catalysis.A ss uch, they are valuables tructures in organic synthesis. Theirs yntheses have been achieved mostly via iodination of functional substrates such as enones, [1] a-silyl/stannyla,b-unsaturated ketones, [2] propargylic alcohols [3] and their ester counterparts, [4] and occasionally via oxidation of iodinated allylica lcohols.[5] Therei ss eldom an approacht hat accomplishesb otho xidation and iodination in ac ollaborative fashion in one step from substrates with lesser degreeso fo xidation/functionalization.[6] Herein, we report an implementation of this approachu sing minimally functionalized internal alkyne substrates. Fort he past several years our group [7] and others [8] have reported the applications of an oxidative gold catalysis strategy in the development of versatiles ynthetic methods. As shown in Approach Ao f Scheme 1A, the coordination of as oft Lewis acidic gold catalyst to aC Ct riple bond triggers the attack of an ucleophilic oxidanta ti ts p bond. Thei nitial adduct can undergo fragmentation of the inherently weak O À Zb ond to offer expedient access to versatile a-oxo gold carbenes;a lternatively,i tm ay proceed to functionalized productsw ithout the carbene intermediacy in the presenceo famore facile reactionp athway.D ue to the catalytic nature of this chemistry,t he in situ generated Au À Cb ond in this class of reactions Scheme1.Replacingg old catalysts with stoichiometric electrophiles in the oxidationo fa lkynes by nucleophilic oxidants.

show abstract

Metallfreie oxidative Cyclisierung von Alkinyl‐Aryl‐Ethern zu Benzofuranonen

Cited by 40 publications

References 50 publications

Zinc‐Catalyzed Alkyne Oxidation/CH Functionalization: Highly Site‐Selective Synthesis of Versatile Isoquinolones and β‐Carbolines

Zinc‐Catalyzed Alkyne Oxidation/CH Functionalization: Highly Site‐Selective Synthesis of Versatile Isoquinolones and β‐Carbolines

Polycomb Determines Responses to Smad2/3 Signaling in Embryonic Stem Cell Differentiation and in Reprogramming

Direct Conversion of Internal Alkynes into α‐Iodoenones: One‐Step Collaborative Iodination and Oxidation

Contact Info

Product

Resources

About