Ruthenium-catalyzed coupling of α-carbonyl phosphoniums with sulfoxonium ylidesviaC-H activation/Wittig reaction sequences
A Ru(ii)-catalyzed coupling of various α-carbonyl phosphoniums with sulfoxonium ylides has been realized for the facile synthesis of 1-naphthols in good to excellent yields. This oxidant-free transformation proceeds through Ru-catalyzed C-H activation of phosphoniums, Ru-carbene insertion, and intramolecular Wittig reaction processes.
Light-enabled, AlCl3-catalyzed regioselective intramolecular nucleophilic addition of non-nucleophilic alkyls to alkynes
Light-enabled, AlCl3-catalyzed regioselective intramolecular nucleophilic cyclization of alkynes using non-nucleophilic alkyls as the nucleophile is reported. Upon photoexcitation, o-alkylphenyl alkynyl ketones can be transferred into (E)-photoenols. Thus, a nucleophilic methylene is formed from the non-nucleophilic alkyl. An AlCl3 catalyst can stabilize the (E)-photoenol intermediate and facilitate further intramolecular nucleophilic cyclization. DFT calculations indicated that the AlCl3-catalyzed cyclization is the regioselectivity determining step.
Zhang, Yanbin,Jin, Ruiwen,Pan, Guangxing,Guo, Hao
supporting information
p. 11621 - 11624
(2020/10/19)
Resolution of Vaulted Biaryl Ligands via Borate Esters of Quinine and Quinidine
Given the sudden and unexplained rise in the cost of (+)- A nd (-)-sparteine, an alternative method for the resolution of vaulted biaryls has been developed. This method involves the reaction of a racemic vaulted biaryl ligand with one equivalent of BH3·SMe2 and one equivalent of either quinine or quinidine. A precipitate then forms from the resulting mixture of diastereomeric borates as a result of differential solubilities. Hydrolysis of the precipitate then liberates the (S)-ligand in the case of quinine and the (R)-ligand in the case of quinidine, both with >99% ee. This method has been applied to 16 different vaulted biaryl ligands, including 10 whose preparation is described here for the first time. In addition, proof of principle has been demonstrated for the dynamic thermodynamic resolution of the vaulted biaryl ligands with this method in combination with a nonchiral copper(II) complex that can racemize the ligand.
Cagnon, Brian R.,Mohammadlou, Aliakbar,Wulff, William D.,Yin, Xiaopeng,Zheng, Li
p. 10432 - 10450
(2020/09/23)
Cu(II)-Catalyzed 6π-Photocyclization of Non-6πSubstrates
This research successfully achieved a Cu(II)-catalyzed 6π-photocyclization of non-6πsubstrates. The photoenolization converts ortho-alkylphenyl alkynl ketones into a triene-type intermediate which undergoes the subsequent 6π-photocyclization to give napht
Zhang, Yanbin,Jin, Ruiwen,Kang, Wenjie,Guo, Hao
supporting information
p. 5502 - 5505
(2020/07/08)
Catalytic Asymmetric Aziridination of Benzhydryl Imines and Diazoacetate Esters with BOROX Catalysts from 3,3′-Disubstituted VANOL Ligands
This work details the synthesis of 22 new chiral VANOL ligands that differ by the nature of the substituent in the 3- and 3′-positions of the ligand. These ligands were incorporated into boroxinate catalysts that were used to screen the catalytic asymmetric aziridination of benzhydryl imines with ethyl diazoacetate. Each catalyst was screened in the reaction of imines generated from benzaldehyde and cyclohexanecarboxaldehyde and some with 4-nitro- and 4-methoxybenzaldehyde. In addition, the first report of the effect of the ester substituent of the diazoacetate ester on the asymmetric induction in these aziridination reactions is presented. The first X-ray structure of a boroxinate catalyst generated from a VANOL-derived ligand is also reported.
Guan, Yong,Lu, Zhenjie,Mohammadlou, Aliakbar,Staples, Richard J.,Wulff, William D.,Yin, Xiaopeng
p. 2073 - 2091
(2020/08/17)
Chemo- and Regioselective Catalyst-Controlled Carbocyclization of Alkynyl Ketones: Rapid Synthesis of 1-Indanones and 1-Naphthols
A catalyst-controlled intramolecular carbocyclization of 2-alkynyl aryl ketones is presented. Under rhodium(III) catalysis, 1-indanones are formed through 5-exo-dig carbocyclizations with exclusive chemo-, regio- and stereoselectivity. When catalyzed by copper(I), 1-naphthols are obtained through 6-endo-dig carbocyclizations with exclusive chemo- and regioselectivity.
Song, Liangliang,Tian, Guilong,Van der Eycken, Erik V.
p. 7645 - 7648
(2019/05/21)
Facile synthesis of 1-naphthols through a copper-catalyzed arylation of methyl ketones with o-bromoacetophenones
The coupling reactions of simple methyl ketones with o-bromoacetophenones and subsquential cyclization reactions were realized to produce a range of 1-naphthols. These cascade reactions were initiated by a rare Cu-catalyzed arylation reaction of methyl ketones with aromatic bromides.
Lou, Zhen-Bang,Pang, Xin-Long,Chen, Chao,Wen, Li-Rong,Li, Ming
supporting information
p. 1231 - 1235
(2015/12/30)
Tandem carbon-carbon bond insertion and intramolecular aldol reaction of benzyne with aroylacetones: Novel formation of 4,4′-disubstituted 1,1′-binaphthols
An efficient route to 4-aryl-2-naphthols from arynes and aroylacetones was developed by carbon-carbon bond insertion followed by an intramolecular aldol reaction and dehydration. Benzyne derived from 2-(trimethylsilyl)phenyl triflate reacted with benzoyla