20017-67-8Relevant articles and documents
Weinreb Amide as Secondary Station for the Dibenzo-24-crown-8 in a Molecular Shuttle
Gauthier, Maxime,Coutrot, Frédéric
, p. 3391 - 3395 (2019)
Here is reported the synthesis of a new molecular shuttle: it consists of a dibenzo-24-crown-8 (DB24C8) that surrounds a molecular axle containing an ammonium group and a newly considered Weinreb amide as stations. At the protonated state the DB24C8 is localized around the best ammonium station, while deprotonation-carbamoylation of the ammonium triggers the shuttling of the macrocycle around the Weinreb amide site. Further post-interlocking modification of the [2]rotaxane was attempted through the cleavage of the Weinreb amide bond using a Grignard reagent. While the non-interlocked molecular axle was cleaved after a short time in mild conditions, the Weinreb amide bond remained unaltered in the [2]rotaxane species over time, even in the presence of a larger amount of Grignard and at a higher temperature, highlighting the protection shield of the macrocycle around the encircled axle.
RHODIUM AND COBALT CATALYSIS OF THE HYDROFORMYLATION AND HYDROGENATION OF 1,1-DIPHENYLETHYLENE
Matsui, Yasushi,Orchin, Milton
, p. 57 - 60 (1983)
Rhodium and cobalt catalyzed reactions of 1,1-diphenylethylene are compared under catalytic hydroformylation conditions (120-180 deg C, 1500-3000 psi H2/CO).With 2 an 85percent yield of aldehyde (hydroformylation) and a 11percent yield of 1,1-diphenylethane (hydrogenation) resulted.With cobalt on the other hand a maximum of 5percent aldehyde and a 95percent yield of hydrocarbon was obtained.The cobalt reaction is very likely free radical in nature while the rhodium reaction involves the conventional olefin insertion into a metal-hydride bond.
Umpolung Strategy for Arene C?H Etherification Leading to Functionalized Chromanes Enabled by I(III) N-Ligated Hypervalent Iodine Reagents
Mikhael, Myriam,Guo, Wentao,Tantillo, Dean J.,Wengryniuk, Sarah E.
supporting information, p. 4867 - 4875 (2021/09/14)
The direct formation of aryl C?O bonds via the intramolecular dehydrogenative coupling of a C?H bond and a pendant alcohol represents a powerful synthetic transformation. Herein, we report a method for intramolecular arene C?H etherification via an umpoled alcohol cyclization mediated by an I(III) N-HVI reagent. This approach provides access to functionalized chromane scaffolds from primary, secondary and tertiary alcohols via a cascade cyclization-iodonium salt formation, the latter providing a versatile functional handle for downstream derivatization. Computational studies support initial formation of an umpoled O-intermediate via I(III) ligand exchange, followed by competitive direct and spirocyclization/1,2-shift pathways. (Figure presented.).
Weinreb Amide, Ketone and Amine as Potential and Competitive Secondary Molecular Stations for Dibenzo-[24]Crown-8 in [2]Rotaxane Molecular Shuttles
Coutrot, Frédéric,Gauthier, Maxime
supporting information, p. 17576 - 17580 (2021/12/09)
This paper reports the synthesis and study of new pH-sensitive DB24C8-based [2]rotaxane molecular shuttles that contain within their axle four potential sites of interaction for the DB24C8: ammonium, amine, Weinreb amide, and ketone. In the protonated state, the DB24C8 lay around the best ammonium site. After either deprotonation or deprotonation-then-carbamoylation of the ammonium, different localizations of the DB24C8 were seen, depending on both the number and nature of the secondary stations and steric restriction. Unexpectedly, the results indicated that the Weinreb amide was not a proper secondary molecular station for the DB24C8. Nevertheless, through its methoxy side chain, it slowed down the shuttling of the macrocycle along the threaded axle, thereby partitioning the [2]rotaxane into two translational isomers on the NMR timescale. The ketone was successfully used as a secondary molecular station, and its weak affinity for the DB24C8 was similar to that of a secondary amine.
Exploring the synthetic potential of a marine transaminase including discrimination at a remote stereocentre
Schwarz, Maria,Murphy, Edel J.,Foley, Aoife M.,Woods, David F.,Castilla, Ignacio Abreu,Reen, F. Jerry,Collins, Stuart G.,O'gara, Fergal,Maguire, Anita R.
supporting information, p. 188 - 198 (2021/01/18)
The marine transaminase, P-ω-TA, can be employed for the transamination from 1-aminotetralins and 1-aminoindanes with differentiation of stereochemistry at both the site of reaction and at a remote stereocentre resulting in formation of ketone products with up to 93% ee. While 4-substituents are tolerated on the tetralin core, the presence of 3- or 8-substituents is not tolerated by the transaminase. In general P-ω-TA shows capacity for remote diastereoselectivity, although both the stereoselectivity and efficiency are dependent on the specific substrate structure. Optimum efficiency and selectivity are seen with 4-haloaryl-1-aminotetralins and 3-haloaryl-1-aminoindanes, which may be associated with the marine origin of this enzyme. This journal is
Method used for reduction of tertiary amide into alcohols and/or amines
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Paragraph 0243-0246, (2019/08/07)
The invention discloses a method used for reduction of tertiary amide into alcohols and/or amines. The method comprises following steps: tertiary amide, an alkali metal reagent, and a proton donor agent are added into an organic solvent for a following reaction selectively: when the proton donor agent is a raw material alcohol and/or inorganic salt aqueous solution, the reaction product is an alcohol compound and/or tertiary amine compound. The method is capable of realizing selective reduction of tertiary amide into alcohols and tertiary amine compounds, the yield is high, the suitable rangeis wide, operation is safe and simple, the adopted raw materials are cheap and easily available; no precious metal catalyst, toxic silanes, and flammable and combustible metal hydrides are adopted; notoxic by product is generated; reaction is more friendly to the environment; problems in the prior art that amide compound reducing method operation is complex, conditions are strict, and control ofproducts is difficult are solved.
Acid-Promoted Hydroformylative Synthesis of Alcohol with Carbon Dioxide by Heterobimetallic Ruthenium-Cobalt Catalytic System
Zhang, Xuehua,Tian, Xinxin,Shen, Chaoren,Xia, Chungu,He, Lin
, p. 1986 - 1992 (2019/03/17)
The acid-aided heterobimetallic ruthenium-cobalt catalytic system for the reductive hydroformylation with carbon dioxide was established. Various alkenes, including waste from biomass and petroleum industry, could be upgraded to valuable alcohols with this protocol. Acid-promoted reverse water-gas shift (RWGS), thereby accelerating the hydroformylative synthesis of alcohol. The theoretical computations revealed that acid promoted RWGS by facilitating the dehydroxylation of ruthenium hydroxy carbonyl intermediate.
Migratory Arylboration of Unactivated Alkenes Enabled by Nickel Catalysis
Wang, Wang,Ding, Chao,Li, Yangyang,Li, Zheqi,Li, Yuqiang,Peng, Long,Yin, Guoyin
supporting information, p. 4612 - 4616 (2019/03/13)
An unprecedented arylboration of unactivated terminal alkenes, featuring 1,n-regioselectivity, has been achieved by nickel catalysis. The nitrogen-based ligand plays an essential role in the success of this three-component reaction. This transformation displays good regioselectivity and excellent functional-group tolerance. In addition, the incorporation of a boron group into the products provides substantial opportunities for further transformations. Also demonstrated is that the products can be readily transformed into pharmaceutically relevant molecules. Unexpectedly, preliminary mechanistic studies indicate that although the metal migration favors the α-position of boron, selective and decisive bond formation is favored at the benzylic position.
Alkyl Ethers as Traceless Hydride Donors in Br?nsted Acid Catalyzed Intramolecular Hydrogen Atom Transfer
Gandamana, Dhika Aditya,Wang, Bin,Tejo, Ciputra,Bolte, Benoit,Gagosz, Fabien,Chiba, Shunsuke
supporting information, p. 6181 - 6185 (2018/05/03)
A new protocol for the deoxygenation of alcohols and the hydrogenation of alkenes under Br?nsted acid catalysis has been developed. The method is based on the use of either a benzyl or isopropyl ether as a traceless hydrogen-atom donor, and involves an intramolecular hydride transfer as a key step, which is achieved in a regio- and stereoselective manner.
Selective Pd-catalyzed hydrogenation of 3,3-diphenylallyl alcohol: Efficient synthesis of 3,3-diarylpropylamine drugs diisopromine and feniprane
Claudino, Thiago S.,Scholten, Jackson D.,Monteiro, Adriano L.
, p. 53 - 56 (2017/09/01)
The Pd-catalyzed selective hydrogenation of C[dbnd]C double bond in (3,3-diphenylallyl)diisopropylamine or 3,3-diphenylallyl alcohol was evaluated using different catalytic systems [Pd/C, Pd(OAc)2/ionic liquid, isolated Pd(0) nanoparticles]. For the (3,3-diphenylallyl)diisopropylamine, hydrogenolysis is preferred over hydrogenation, and only moderate selectivities were obtained for the desired product. However, complete conversion and 100% selectivity were obtained for the hydrogenation of 3,3-diphenylallyl alcohol using isolated Pd(0) nanoparticles under mild condition. This successful strategy enabled the effective synthesis of diisopromine and feniprane drugs and opens new possibilities for the preparation of other biologically active compounds.
