91047-77-7Relevant academic research and scientific papers
Synthesis of Enantioenriched 3,4-Disubstituted Chromans through Lewis Base Catalyzed Carbosulfenylation
Denmark, Scott E.,Laverny, Aragorn,Menard, Travis
, p. 14290 - 14310 (2021/11/12)
A method for the catalytic, enantioselective, carbosulfenylation of alkenes to construct 3,4-disubstituted chromans is described. Alkene activation proceeds through the intermediacy of enantioenriched, configurationally stable thiiranium ions generated from catalytic, Lewis base activation of an electrophilic sulfenylating agent. The transformation affords difficult-to-generate, enantioenriched, 3,4-disubstituted chromans in moderate to high yields and excellent enantioselectivities. A variety of substituents are compatible including electronically diverse functional groups as well as several functional handles such as aryl halides, esters, anilines, and phenols. The resulting thioether moiety is amenable to a number of functional group manipulations and transformations. Notably, the pendant sulfide was successfully cleaved to furnish a free thiol which readily provides access to most sulfur-containing functional groups which are present in natural products and pharmaceuticals.
Enantiodivergent One-Pot Synthesis of Axially Chiral Biaryls Using Organocatalyst-Mediated Enantioselective Domino Reaction and Central-to-Axial Chirality Conversion
Hayashi, Yujiro,Koshino, Seitaro,Kwon, Eunsang,Monde, Kenji,Taniguchi, Tohru
supporting information, p. 15786 - 15794 (2021/10/14)
Enantiodivergent one-pot synthesis of biaryls was developed using a catalytic amount of a single chiral source. A domino organocatalyst-mediated enantioselective Michael reaction and aldol condensation provided centrally chiral dihydronaphthalenes with excellent enantioselectivity, from which an enantiodivergent chirality conversion from central-to-axial chirality was achieved. Both enantiomers of biaryls were obtained with excellent enantioselectivity. All transformations can be conducted in a single reaction vessel. A plausible reaction mechanism for the enantiodivergence is proposed.
A One-Pot Synthesis of α,β-Unsaturated Esters From Esters
Hong, Chang Whee,Lee, Yong Jin,An, Duk Keun
, p. 1121 - 1125 (2021/06/01)
A convenient method for reductive Horner–Wadsworth–Emmons (HWE) olefination is described. The E-selective HWE homologation of various esters to α,β-unsaturated esters was readily achieved and gave the desired products in good-to-moderate yields under mild conditions. The one-pot reaction proceeds through an in situ generated aldehyde, formed via the partial reduction of an ester with lithium diisobutyl-t-butoxyaluminum hydride. The formation of cyclized metal acetal and subsequent decompose to the aldehyde for the olefination was found to be a crucial step in this C2-carbon homologation protocol.
Hypervalent iodine(iii) induced oxidative olefination of benzylamines using Wittig reagents
Ramavath, Vijayalakshmi,Rupanawar, Bapurao D.,More, Satish G.,Bansode, Ajay H.,Suryavanshi, Gurunath
, p. 8806 - 8813 (2021/05/26)
We have developed hypervalent iodine(iii) induced oxidative olefination of primary and secondary benzylamines using 2C-Wittig reagents, which provides easy access to α,β-unsaturated esters. Mild reaction conditions, good to excellent yields with high (E) selectivity, and a broad substrate scope are the key features of this reaction. We have successfully carried out the gram-scale synthesis of α,β-unsaturated esters.
Solvent role in the lipase-catalysed esterification of cinnamic acid and derivatives. Optimisation of the biotransformation conditions
Suárez-Escobedo, Laura,Gotor-Fernández, Vicente
, (2021/02/05)
The esterification of cinnamic acid has been deeply investigated using ethanol as nucleophile and Candida antarctica lipase type B (CAL-B) as suitable biocatalyst. Special attention has been paid to the role that the solvent plays in the production of ethyl cinnamate. Therefore, volatile organic solvents and deep eutectic mixtures were employed in order to find optimal reaction conditions. Once that hexane was selected as the solvent of choice, other parameters that affect the enzyme activity were investigated in order to produce ethyl cinnamate with excellent yield. The CAL-B loading, nucleophile equivalents, temperature and reaction time have been identified as key parameters in the enzyme efficiency, and the potential of lipase-catalysed esterification has been finally exploited to produce a series of ethyl esters with different pattern substitutions on the aromatic ring.
Tandem Copper-Catalyzed Regioselective N-Arylation-Aza-Michael Addition: Synthesis of Tetracyclic 5 H-Benzothiazolo[3,2- a]quinazoline Derivatives
Honnanayakanavar, Jyoti M.,Harish, Battu,Nanubolu, Jagadeesh Babu,Suresh, Surisetti
supporting information, p. 8780 - 8791 (2020/08/28)
A copper-catalyzed tandem process integrating regioselective N-arylation, followed by aza-Michael addition, is disclosed using 2-aminobenzothiazoles and ortho-halo cinnamic acid congeners. This process generated diverse tetracyclic 5H-benzothiazolo[3,2-a]quinazoline derivatives in moderate to good yields. The present tandem reaction appears to proceed through concomitant ring opening of 2-aminobenzothiazole and S-arylation to give the ortho-cyanamide-substituted diaryl thioether intermediate. The thus generated intermediate likely undergoes an unprecedented Truce-Smiles-type rearrangement involving S- to N-aryl migration, followed by reformation of the thiazole ring and intramolecular aza-Michael addition to furnish the title products.
Enantioselective Syntheses of Strychnos and Chelidonium Alkaloids through Regio- and Stereocontrolled Cooperative Catalysis
Fyfe, James W. B.,Hutchings-Goetz, Luke S.,Snaddon, Thomas N.,Yang, Chao
supporting information, p. 17556 - 17564 (2020/08/14)
We describe enantioselective syntheses of strychnos and chelidonium alkaloids. In the first case, indole acetic acid esters were established as excellent partner nucleophiles for enantioselective cooperative isothiourea/Pd catalyzed α-alkylation. This provides products containing indole-bearing stereocenters in high yield and with excellent levels of enantioinduction in a manner that is notably independent of the N-substituent. This led to concise syntheses of (?)-akuammicine and (?)-strychnine. In the second case, the poor performance of ortho-substituted cinnamyl electrophiles in the enantioselective cooperative isothiourea/Ir catalyzed α-alkylation was overcome by appropriate substituent choice, leading to enantioselective syntheses of (+)-chelidonine, (+)-norchelidonine, and (+)-chelamine.
Selective Synthesis of Z-Cinnamyl Ethers and Cinnamyl Alcohols through Visible Light-Promoted Photocatalytic E to Z Isomerization
Li, Hengchao,Chen, Hang,Zhou, Yang,Huang, Jin,Yi, Jundan,Zhao, Hongcai,Wang, Wei,Jing, Linhai
supporting information, p. 555 - 559 (2020/02/05)
A photocatalytic E to Z isomerization of alkenes using an iridium photosensitizer under mild reaction conditions is disclosed. This method provides scalable and efficient access to Z-cinnamyl ether and allylic alcohol derivatives in high yields with excellent stereoselectivity. Importantly, this method also provides a powerful strategy for the selective synthesis of Z-magnolol and honokiol derivatives possessing potential biological activity.
Bioinspired Radical Stetter Reaction: Radical Umpolung Enabled by Ion-Pair Photocatalysis
Morack, Tobias,Mück-Lichtenfeld, Christian,Gilmour, Ryan
supporting information, p. 1208 - 1212 (2019/01/04)
A bioinspired, intermolecular radical Stetter reaction of α-keto acids and aldehydes is disclosed that is contingent on a formal “radical umpolung” concept. Enabled by secondary amine activation, electrostatic recognition ensures that the α-ketocarboxylic acids, which function as latent acyl radicals, are proximal to the in situ generated iminium salts. This photoactive contact ion pair is an electron donor–acceptor (EDA) complex, and undergoes facile single electron transfer (SET) and rapid decarboxylation prior to radical–radical recombination. Importantly, decarbonylation is mitigated by this strategy. The initial computational validation on which the process is predicated matches closely with experiment. Synergising organo- and photocatalysis activation principles finally expands the mechanistic and synthetic scope of the classic Stetter reaction to include α,β-unsaturated aldehydes as acceptors.
Sequential Palladium-Catalyzed Allylic Alkylation/retro-Dieckmann Fragmentation Strategy for the Synthesis of α-Substituted Acrylonitriles
Katsina, Tania,Sharma, Sachi Prem,Buccafusca, Roberto,Quinn, Derek J.,Moody, Thomas S.,Arseniyadis, Stellios
supporting information, p. 9348 - 9352 (2019/11/20)
A straightforward synthesis of α-substituted acrylonitriles is described using 4-cyano-3-oxotetrahydro-thiophene (c-THT) as an acrylonitrile surrogate. This unprecedented two-step sequence featuring a palladium-catalyzed allylic alkylation (Pd-AA) and a retro-Dieckmann fragmentation provides a general entry into diversely substituted 1,4-dienes.
