287929-73-1Relevant academic research and scientific papers
Regio- And diastereoselective Pd-catalyzed aminochlorocyclization of allylic carbamates: scope, derivatization, and mechanism
Ariga, Elaine Miho,Carita Correra, Thiago,Matsushima, Jullyane Emi,McIndoe, J. Scott,Moreira Ribeiro, Francisco Wanderson,Omari, Isaac,Papa Spadafora, Bruna,Rodrigues, Alessandro,Soares, Priscila Machado Arruda,Vinhato, Elisangela,de Oliveira-Silva, Diogo
supporting information, p. 5595 - 5606 (2021/07/02)
The regio- and diastereoselective synthesis of oxazolidinonesviaa Pd-catalyzed vicinal C-N/C-Cl bond-forming reaction from internal alkenes of allylic carbamates is reported. The oxazolidinones are obtained in yields of 44 to 95% with high to excellent diastereoselectivities (from 6?:?1 to >20?:?1 dr) from readily available precursors. This process is scalable, and the products are suitable for the synthesis of useful amino alcohols. A detailed theoretical and experimental mechanistic study was carried out to describe that the reaction proceeds through ananti-aminopalladation of the alkene followed by an oxidative C-Pd(ii) cleavage with retention of the carbon stereochemistry to yield the major diastereomer. The role of Cu(ii) in a C-Cl bond-forming mechanism step has also been proposed.
Boron-Templated Dimerization of Allylic Alcohols to Form Protected 1,3-Diols via Acid Catalysis
Nazari, S. Hadi,Forson, Kelton G.,Martinez, Erin E.,Hansen, Nicholas J.,Gassaway, Kyle J.,Lyons, Nathan M.,Kenney, Karissa C.,Valdivia-Berroeta, Gabriel A.,Smith, Stacey J.,Michaelis, David J.
, p. 9589 - 9593 (2019/12/02)
We report an unprecedented boron-templated dimerization of allylic alcohols that generates a 1,3-diol product with two stereogenic centers in high yield and diastereoselectivity. This acid-catalyzed reaction is achieved via in situ formation of a boronic ester intermediate that facilitates selective cyclization and formation of a cyclic boronic ester product. High yields are observed with a variety of allylic alcohols, and mechanistic studies confirm the role of boron as a template for the reaction.
Biphilic organophosphorus catalysis: Regioselective reductive transposition of allylic bromides via PIII/PV redox cycling
Reichl, Kyle D.,Dunn, Nicole L.,Fastuca, Nicholas J.,Radosevich, Alexander T.
supporting information, p. 5292 - 5295 (2015/05/13)
We report that a regioselective reductive transposition of primary allylic bromides is catalyzed by a biphilic organophosphorus (phosphetane) catalyst. Spectroscopic evidence supports the formation of a pentacoordinate (σ5-P) hydridophosphorane as a key reactive intermediate. Kinetics experiments and computational modeling are consistent with a unimolecular decomposition of the σ5-P hydridophosphorane via a concerted cyclic transition structure that delivers the observed allylic transposition and completes a novel PIII/PV redox catalytic cycle. These results broaden the growing repertoire of reactions catalyzed within the PIII/PV redox couple and suggest additional opportunities for organophosphorus catalysis in a biphilic mode.
An efficient enzymatic approach to (S)-1-aryl-allylamines
Knezevic, Anamarija,Landek, Goran,Dokli, Irena,Vinkovic, Vladimir
experimental part, p. 936 - 941 (2011/09/20)
A range of 1-aryl-allylamines were prepared in moderate to excellent enantioselectivity (ee 63.5%→99.9%) using lipase B from a Candida antarctica catalyzed resolution of racemic amines. This is the first time that CaLB has been used for the resolution of 1-aryl-allylamines. Racemic amines were prepared starting from aromatic aldehydes with a [3,3]-sigmatropic rearrangement of the acyclic imidates as the key step followed by trichloroacetamidate hydrolysis. Aldehydes were converted into acrylic esters using Knoevenagel reaction. After reduction, the corresponding alcohols were used for the preparation of trichloroacetimidates, which were then used in an Overman rearrangement.
Palladium-catalyzed allylic fluorination
Hollingworth, Charlotte,Hazari, Amaruka,Hopkinson, Matthew N.,Tredwell, Matthew,Benedetto, Elena,Huiban, Mickael,Gee, Antony D.,Brown, John M.,Gouverneur, Veronique
supporting information; experimental part, p. 2613 - 2617 (2011/05/03)
Mild and rapid: The title reaction is presented and its applicability to 18F radiolabeling is demonstrated (see scheme; TBAF=tetra-n- butylammonium fluoride, THF=tetrahydrofuran, dba=dibenzylideneacetone). The use of p-nitrobenzoate as the leaving group is significant to the success of this catalytic organometallic fluorination process. A range of allylic fluorides were synthesized by this method. Copyright
Ruthenium-catalyzed synthesis of allylic alcohols: Boronic acid as a hydroxide source
Bouziane, Asmae,Helou, Marion,Carboni, Bertrand,Carreaux, Francois,Demerseman, Bernard,Bruneau, Christian,Renaud, Jean-Luc
experimental part, p. 5630 - 5637 (2009/05/27)
Secondary allylic alcohols were synthesized from linear allylic halides or carbonates using a catalytic amount of a ruthenium complex in the presence of boronic acid. The effects of solvent, base, ruthenium precursor, and boronic acid were fully explored, and the scope of the reaction was extended to various sub-strates. We also describe a preliminary investigation towards an enantioselective process.
Enantioselective syntheses of conformationally rigid, highly lipophilic mesityl-substituted amino acids
Medina, Eva,Moyano, Albert,Pericas, Miquel A.,Riera, Antoni
, p. 972 - 988 (2007/10/03)
Three N-Boc-protected amino acids substituted with a mesityl (=2,4,6- trimethylphenyl) group were synthesized in enantiomerically pure form, either by asymmetric epoxidation or by aminohydroxylation as the source of chirality. The 3-mesityloxirane-2-methanol 7, easily available in high enantiomer purity by Sharpless epoxidation, was converted into 3-{[(tert- butoxy)carbonyl]amino}-3-mesitylpropane-1,2-diol 9 by a regio- and stereoselective ring opening with an ammonia equivalent (sodium azide or benzhydrylamine), followed by hydrogenation and in situ treatment with (Boc)2O (Boc=[(tert-butoxy)carbonyl]) (Scheme 3). Oxidative cleavage of the diol fragment in 9 afforded N-[(tert-butoxy)carbonyl]-α-mesitylglycine 1 of >99% ee. This amino acid was also prepared in enantiomerically pure form starting from 2,4,6-trimethylstyrene (11) by a regioselective Sharpless asymmetric aminohydroxylation, followed by a 2,2,6,6-tetramethylpiperidin-1- yloxyl (TEMPO)-catalyzed oxidation (Scheme 4). On the other hand, 1-[(tert- butoxy)carbonyl]-2-{{[(tert-butyl)dimethylsilyl]oxy}methyl}-3- mesitylaziridine 14 was prepared from 9 by a sequence involving selective protection of the primary alcohol (as a silyl ether), activation of the secondary alcohol as a mesylate, and base-induced (NaH) cyclization (Scheme 5). The reductive cleavage of the aziridine ring (H2, Pd/C), followed by alcohol deprotection (Bu4NF/THF) and oxidation (pyridinium dichromate (PDC)/DMF or (TEMPO)/NaClO) provided, in high yield and enantiomeric purity, N-[(tert-butoxy)carbonyl]-β-mesitylalanine 2. Alternatively, the regioselective ring opening of the aziridine ring of 14 with lithium dimethylcuprate, followed by silyl-ether cleavage and oxidation lead to N- [(tert-butoxy)carbonyl]-β-mesityl-β-methylalanine 3. A conformational study of the methyl esters of the N-Boc-protected amino acids 1 and 3 carried out by variable-temperature 1H-NMR and semi-empirical (AM1) calculations shows the strong rotational restriction imposed by the mesityl group.
