121671-77-0Relevant academic research and scientific papers
Primary Anion–π Catalysis of Epoxide-Opening Ether Cyclization into Rings of Different Sizes: Access to New Reactivity
Matile, Stefan,Paraja, Miguel
supporting information, p. 6273 - 6277 (2020/02/28)
The concept of anion–π catalysis focuses on the stabilization of anionic transition states on aromatic π surfaces. Recently, we demonstrated the occurrence of epoxide-opening ether cyclizations on aromatic π surfaces. Although the reaction proceeded through unconventional mechanisms, the obtained products are the same as those from conventional Br?nsted acid catalysis, and in agreement with the Baldwin selectivity rules. Different mechanisms, however, should ultimately lead to new products, a promise anion–π catalysis has been reluctant to live up to. Herein, we report non-trivial reactions that work with anion–π catalysis, but not with Br?nsted acids, under comparable conditions. Namely, we show that the anion–π templated autocatalysis and epoxide opening with alcoholate–π interactions can provide access to unconventional ring chemistry. For smaller rings, anion–π catalysis affords anti-Baldwin oxolanes, 2-oxabicyclo[3.3.0]octanes, and the expansion of Baldwin oxetanes by methyl migration. For larger rings, anion–π templated autocatalysis is thought to alleviate the entropic penalty of folding to enable disfavored anti-Baldwin cyclizations into oxepanes and oxocanes.
Chemoselective Oxidation of p-Methoxybenzyl Ethers by an Electronically Tuned Nitroxyl Radical Catalyst
Hamada, Shohei,Sugimoto, Koichi,Elboray, Elghareeb E.,Kawabata, Takeo,Furuta, Takumi
supporting information, p. 5486 - 5490 (2020/07/24)
The oxidation of p-methoxy benzyl (PMB) ethers was achieved using nitroxyl radical catalyst 1, which contains electron-withdrawing ester groups adjacent to the nitroxyl group. The oxidative deprotection of the PMB moieties on the hydroxy groups was observed upon treatment of 1 with 1 equiv of the co-oxidant phenyl iodonium bis(trifluoroacetate) (PIFA). The corresponding carbonyl compounds were obtained by treating the PMB-protected alcohols with 1 and an excess of PIFA.
Structure–activity relationship studies of atpenin A5 analogs with chemical modification of the side chain moiety
Ohtawa, Masaki,Yano, Keisuke,Miyao, Atsuyoshi,Hiura, Tohru,Sugiyama, Kouhei,Arima, Shiho,Kita, Kiyoshi,Omura, Satoshi,Nagamitsu, Tohru
supporting information, p. 1037 - 1042 (2019/03/21)
We designed and synthesized new atpenin A5 analogs for SAR study. Most of the analogs lacked one or several functional groups in the side chain of atpenin A5, and the stereoisomers proved to be weak nematode complex II inhibitors. However, we determined t
Development of Hybrid Phospholipid Mimics as Effective Agonists for Liver Receptor Homologue-1
Flynn, Autumn R.,Mays, Suzanne G.,Ortlund, Eric A.,Jui, Nathan T.
supporting information, p. 1051 - 1056 (2018/09/21)
The orphan nuclear receptor Liver Receptor Homologue-1 (LRH-1) is an emerging drug target for metabolic disorders. The most effective known LRH-1 modulators are phospholipids or synthetic hexahydropentalene compounds. While both classes have micromolar ef
Expanding the scope of methyl xanthate esters - From Barton-McCombie reaction auxiliary to versatile protective group
Thorsheim, Karin,Manner, Sophie,Ellervik, Ulf
, p. 6329 - 6333 (2017/09/29)
The methyl xanthate ester is presented as a versatile protective group for alcohols. Hydroxyl groups can easily be transformed into methyl xanthate esters by several methods and are commonly used as an auxiliary in the Barton-McCombie reaction. We show that these methyl xanthate esters can readily and chemoselectively be cleaved under mild conditions by the action of diethylenetriamine using microwave heating. This method is orthogonal to many common hydroxyl protective groups that can be introduced and cleaved in the presence of methyl xanthate ester.
Electrochemical Deprotection of para-Methoxybenzyl Ethers in a Flow Electrolysis Cell
Green, Robert A.,Jolley, Katherine E.,Al-Hadedi, Azzam A. M.,Pletcher, Derek,Harrowven, David C.,De Frutos, Oscar,Mateos, Carlos,Klauber, David J.,Rincón, Juan A.,Brown, Richard C. D.
supporting information, p. 2050 - 2053 (2017/04/27)
Electrochemical deprotection of p-methoxybenzyl (PMB) ethers was performed in an undivided electrochemical flow reactor in MeOH solution, leading to the unmasked alcohol and p-methoxybenzaldehyde dimethyl acetal as a byproduct. The electrochemical method removes the need for chemical oxidants, and added electrolyte (BF4NEt4) can be recovered and reused. The method was applied to 17 substrates with high conversions in a single pass, yields up to 92%, and up to 7.5 g h-1 productivity. The PMB protecting group was also selectively removed in the presence of some other common alcohol protecting groups.
Mild and selective deprotection of tert -butyl(dimethyl)silyl ethers with catalytic amounts of sodium tetrachloroaurate(III) dihydrate
Zhang, Qi,Kang, Xiuqin,Long, Lei,Zhu, Lijuan,Chai, Yonghai
, p. 55 - 64 (2015/02/02)
A simple and mild method for the removal of tert-butyl(dimethyl)silyl (TBS) protecting groups with catalytic amounts of sodium tetrachloroaurate(III) dihydrate is described. The procedure permits selective deprotection of aliphatic TBS ethers in good to excellent yields in the presence of aromatic TBS ethers, aliphatic triisopropylsilyl ethers, aliphatic tert-butyl(diphenyl)silyl ethers, or sterically hindered aliphatic TBS ethers. Additionally, TBS ethers can also be transformed into 4-methoxybenzyl ethers or methyl ethers in one pot by using larger quantities of the catalyst and a higher reaction temperature.
Photoredox removal of p-methoxybenzyl ether protecting group with hydrogen peroxide as terminal oxidant
Liu, Zheng,Zhang, Yi,Cai, Zheren,Sun, Hao,Cheng, Xu
supporting information, p. 589 - 593 (2015/03/05)
We report a mild protocol for removal of the p-methoxybenzyl ether protecting group under acidic conditions with eosin Y combined with LEDs as a photoredox catalysis system and hydrogen peroxide as the terminal oxidant. This protocol is compatible with ethers derived from primary, secondary, and tertiary alcohols, as well as with various functional groups. The protocol showed unusual selectivity for a tertiary ether over a primary ether. The scale up to gram scale is also explored and identical reactivity is observed.
METHOD FOR PRODUCING CARBOXYLIC ACID AND ALCOHOL BY HYDROLYSIS OF ESTER
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Paragraph 0066; 0067; 0068, (2014/11/13)
As shown by the following formula (1), after methyl laurate (2 mmol) and water (8 mL) are added to an ammonium pyrosulfate catalyst (5 mol%), a hydrolysis reaction of methyl laurate is carried out by heating for 24 hours at 60°C while stirring is performed, so that lauric acid can be obtained with a yield of 86%.
Enantioselective intramolecular aldehyde α-alkylation with simple olefins: Direct access to homo-ene products
Comito, Robert J.,Finelli, Fernanda G.,Macmillan, David W. C.
supporting information, p. 9358 - 9361 (2013/07/26)
A highly selective method for the synthesis of asymmetrically substituted carbocycles and heterocycles from unactivated aldehyde-olefin precursors has been achieved via enantioselective SOMO-catalysis. Addition of a catalytically generated enamine radical cation across a pendent olefin serves to establish a general asymmetric strategy toward the production of a wide range of formyl-substituted rings with alkene transposition. Conceptually, this novel mechanism allows direct access to "homo-ene"-type products.
