- Substrate-Induced Dimerization Assembly of Chiral Macrocycle Catalysts toward Cooperative Asymmetric Catalysis
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An artificial system of substrate-induced dimerization assembly of chiral macrocycle catalysts enables a highly cooperative hydrogen-bonding activation network for efficient enantioselective transformation. These macrocycles contain two thiourea and two chiral diamine moieties and dimerize with sulfate to form a sandwich-like assembly. The macrocycles then adopt an extended conformation and reciprocally complement the hydrogen-bonding interaction sites. Inspired by the guest-induced dynamic assembly, these macrocycles catalyze the decarboxylative Mannich reaction of cyclic aldimines containing a sulfamate heading group. The imine substrate can be activated toward nucleophilic attack of β-ketoacid by a cooperative hydrogen-bonding network enabled by sulfamate-induced dimerization assembly of the macrocycle catalysts. Highly efficient (>95 % yield in most cases) and enantioselective (up to 97.5:2.5 er) transformation of a variety of substrates using only 5 mol % macrocycle was achieved.
- Ao, Yu-Fei,Guo, Hao,Meng, Wei,Wang, De-Xian,Wang, Qi-Qiang,Zhang, Lie-Wei,Zhou, Hao
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supporting information
p. 2623 - 2627
(2020/02/04)
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- Development of Chiral Organosuperbase Catalysts Consisting of Two Different Organobase Functionalities
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In the field of chiral Br?nsted base catalysis, a new generation of chiral catalysts has been highly anticipated to overcome the intrinsic limitation of pronucleophiles that are applicable to the enantioselective reactions. Herein, we reveal conceptually new chiral Br?nsted base catalysts consisting of two different organobase functionalities, one of which functions as an organosuperbase and the other as the substrate recognition site. Their prominent activity, which stems from the distinctive cooperative function by the two organobases in a single catalyst molecule, was demonstrated in the unprecedented enantioselective direct Mannich-type reaction of α-phenylthioacetate as a less acidic pronucleophile. The present achievement would provide a new guiding principle for the design and development of chiral Br?nsted base catalysts and significantly broaden the utility of Br?nsted base catalysis in asymmetric organic synthesis.
- Kondoh, Azusa,Oishi, Masafumi,Terada, Masahiro,Tezuka, Hikaru
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supporting information
p. 7472 - 7477
(2020/03/19)
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- Dynamic Kinetic Resolution of Heterobiaryl Ketones by Zinc-Catalyzed Asymmetric Hydrosilylation
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A diastereo- and highly enantioselective dynamic kinetic resolution (DKR) of configurationally labile heterobiaryl ketones is described. The DKR proceeds by zinc-catalyzed hydrosilylation of the carbonyl group, thus leading to secondary alcohols bearing axial and central chirality. The strategy relies on the labilization of the stereogenic axis that takes place thanks to a Lewis acid–base interaction between a nitrogen atom in the heterocycle and the ketone carbonyl group. The synthetic utility of the methodology is demonstrated through stereospecific transformations into either N,N-ligands or appealing axially chiral, bifunctional thiourea organocatalysts.
- Hornillos, Valentín,Carmona, José A.,Ros, Abel,Iglesias-Sigüenza, Javier,López-Serrano, Joaquín,Fernández, Rosario,Lassaletta, José M.
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supporting information
p. 3777 - 3781
(2018/03/21)
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- Vanadium(I) chloride and lithium vanadium(I) dihydride as selective epimetallating reagents for π- and σ-bonded organic substrates
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Subvalent vanadium(I) salts, of empirical formulas, VCl, vanadium(I) chloride and LiVH2, lithium vanadium(I) dihydride, whose efficient preparation, structural constitution and mode of reaction toward certain organic substrates have been described in a preceding article, are here evaluated in their reactions toward a wide variety of π- and σ-bonded organic substrates, namely carbonyl, imine, azo, alkene, 1,3-diene, nitrile π-bonds and C-X, C-O, C-N and N-N σ-bonds. Compared with the high reactivity of CrCl and LiCrH2 reagents in attacking both types of bonds, the VCl and LiVH2 reagents were much milder and selective in epimetallating π-bonds, often forming the 1:1 adduct of LiVH2 and π-bonded substrate as the major product. Finally, the vanadium reagents showed little tendency to cleave C-O, C-S and C-N bonds and a smaller scope in cleaving C-X bonds than their chromium counterparts. Because of their selectivity these vanadium reagents offer the following preparative promise: 1) smooth McMurry carbonyl coupling to their reductive dimers; 2) deoxygenation of epoxides; 3) selective aromatic C-X reduction; 4) high yields of epimetallated carbonyls or imines as intermediates to α-hydroxy and α-amino acids; 5) 1,4-reductions of 1,3-alkadienes; 6) reductive dimerization of nitriles to ketones; 7) 1,4 or 1,n-epimetallations leading to acyloins or indoles; and 8) reductive dimerizations of azines to produce unusual imidazole derivatives. In explaining the greater kinetic stability of the 1:1 LiVH2 adduct with carbonyl or imine substrates it is pointed out that such epimetallated adducts from LiVH2 would likely be diamagnetic, whereas such adducts from LiCrH2 have an unpaired electron on the Cr center and hence would rupture, so that the electron would be on the C center. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Eisch, John J.,Fregene, Paul O.
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scheme or table
p. 4482 - 4492
(2009/05/07)
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- Synthesis, resolution, and application of 2,2′-bis(diphenylphosphino) -3,3′-binaphtho[b]furan (BINAPFu)
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(±)-2,2′-Bis(diphenylphosphino)-3,3′-binaphtho[2,1-b] furan (BINAPFu) was synthesized from 2-naphthoxyacetic acid in a five-step sequence in 62% overall yield. A variety of reported resolution procedures for biaryl bisphosphines did not work with (±)-BINAPFu; thus, a new resolution method was developed, involving the Staudinger reaction of the aforementioned racemate of BINAPFu with an enantiopure camphor sulfonyl azide derivative. The resulting diastereomeric phosphinimines were separated by flash chromatography. Subsequent hydrolysis to the corresponding bis-phosphine oxide and trichlorosilane reduction provided enantiopure BINAPFu. The absolute stereochemical configuration of BINAPFu was established by X-ray crystallography. BINAPFu was compared with commercially available 2,2′-bis(diphenylphosphino)-1,1′-binaphthalene (BINAP) in Pd(0)-catalyzed intermolecular Heck reactions. Investigation of the Heck arylation of 2,3-dihydrofuran showed BINAPFu to be more efficacious than BINAP in dioxane at 30°C. A variety of phosphorus selenides were prepared, and the 1JP-Se coupling constants measured, to obtain a comparative scale of parent phosphine basicity. The phosphorus atoms in BINAPFu were found to be electron deficient when compared with BINAP but slightly more electron rich than trifurylphosphine.
- Andersen, Nell G.,Parvez, Masood,McDonald, Robert,Keay, Brian A.
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p. 145 - 161
(2007/10/03)
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- An efficient method for the synthesis of N,N′-dimethyl-1,2-diamines
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A simple method for the preparation of N,N′-dimethyl-1,2-diamines is described. The method requires the dimethylation of a diazaphospholidine oxide followed by acid-catalysed hydrolysis.
- Tye, Heather,Eldred, Colin,Wills, Martin
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p. 155 - 158
(2007/10/03)
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- Synthesis of chiral azamacrocycles using the bis(α-chloroacetamide)s derived from chiral 1,2-diphenylethylenediamine
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Optically active diphenyl-substituted tetraaza-12-crown-4 diamide (10), tetraaza-15-crown-5 diamide (12), tetraaza-18-crown-6 diamide (11), and hexaaza-18-crown-6 diamide (9) ligands were prepared by treating the appropriate secondary diamines with the (R,R)- and (S,S)- forms of 1,2- bis(N-methyl-α-chloracetamido)-1,2diphenylethane (20). Macrocyclic diamides 9 and 10 were reduced to form the optically active diphenyl-substituted hexaaza-18-crown-6 (13) and tetraaza-12-crown-4 (14), respectively. Reduction of macrocyclic diamide ligands 11 and 12 gave a complex mixture of products from which the desired tetraaza-15-crown-5 and 18-crown-6 compounds could not be isolated. Dichloride 20 was prepared by treating the chiral forms of 1,2- diphenylethylenediamine with chloroacetic anhydride or chloroacetyl chloride. The crystal structures for the (R,R)-form of dichloride 20 and the (S,S)-forms of macrocycles 10 and 11 are reported.
- Hu, Kejiang,Krakowiak, Krzysztof E.,Bradshaw, Jerald S.,Dalley, N. Kent,Xue, Guoping,Izatt, Reed M.
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p. 347 - 354
(2007/10/03)
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- Synthesis of phosphoramides for the lewis base-catalyzed allylation and aldol addition reactions
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Both chiral and achiral phosphoramides of diverse structure were prepared from diamines by the coupling to phosphorus(V) or phosphorus(III) reagents. Several enantiopure 1,2-diphenyl-1,2-ethanediamine analogues have been prepared by the reductive coupling of the corresponding N-silylimine with NbCl4(THF)2 and subsequent resolution by the formation of diastereomeric menthyl carbamates. (S,S)-N,N'-Di-(1-naphthyl)-1,2-diphenyl- 1,2-ethanediamine 15 was prepared by the arylation of (S,S)-1,2-diphenyl- 1,2-ethanediamine with naphthyl iodide.
- Denmark, Scott E.,Su, Xiping,Nishigaichi, Yutaka,Coe, Diane M.,Wong, Ken-Tsung,Winter, Stephen B. D.,Choi, Jun Young
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p. 1958 - 1967
(2007/10/03)
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- Stereoselective pinacol coupling of planar chiral (benzaldehyde)Cr(Co)3, (benzaldimine)Cr(CO)3, ferrocenecarboxaldehyde and (dienal)Fe(CO)3 complexes with samarium diiodide
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An intermolecular pinacol coupling of the Planar chiral tricarbonylchromium complexes of o-substituted benzaldehydes or benzaldimines with samarium(II) diiodide in THF produces exclusively threo 1.2-diols or 1,2-diamines in an optically pure form, while the corresponding racemic o- substituted benzaldehyde or benzaldimine chromium complexes give a mixture of threo and erythro pinacol coupling products in a various ratio depending upon the nature of o-substituent. Similarly, planar chiral 2-substituted ferrocenecarboxaldehydes and (dienal)Fe(CO)3 produce the corresponding 1.2- diols with high stereoselectivity. The generated transition metal-complexed ketyl radical intermediates are configurationally stable with restriction to a rotation about C(α)-C(ipso) bond.
- Taniguchi, Nobukazu,Uemura, Motokazu
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p. 12775 - 12788
(2007/10/03)
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- Isomerization of meso diamines into their C2 symmetrical d,l isomers
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An efficient isomerization method is disclosed which allows the obtention of the useful d,l isomers of C2 symmetrical diamines, starting from their meso isomer.
- Alexakis, Alexandre,Aujard, Isabelle,Mangeney, Pierre
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p. 875 - 876
(2007/10/03)
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- Practical and efficient synthesis of C2 symmetrical diamines with Zn / Me3SiCl
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C2 symmetrical diamines are efficiently obtained by reductive coupling of imines with the couple Zn/Me3SiCl. This high yielding method is very practical and cheap for large scale preparation.
- Alexakis, Alexandre,Aujard, Isabelle,Mangeney, Pierre
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p. 873 - 874
(2007/10/03)
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- Synthesis of Enantiomerically Pure 1,2-Diamines by Reductive Coupling of Tricarbony(benzaldimine)chromium Complexes
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Enantiomerically pure 1,2-diamines are prepared by intermolecular pinacol coupling of planar chiral (benzaldimine)Cr(CO)3 complexes with samarium(II) diiodide.
- Taniguchi, Nobukazu,Uemura, Motokazu
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- Diastereoselective Cycloaddition of N-Lithiated Azomethine Ylides to (E)-α,β-Unsaturated Esters Bearing a C2-Symmetric Imidazolidine Chiral Controller
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The 1,3-dipolar cycloaddition of N-metalated ylides to chiral (E)-3-(1,3-disubstituted 4,5-diphenylimidazolidin-2-yl)propenoates proceeded highly diastereoselectively.The previously unknown absolute configuration of optically pure 1,2-dianilino-1,2-diphenylethane was determined from the absolute configuration of the cycloadducts.What diastereotopic olefin face of the α,β-unsaturated ester was attacked by the ylide was found to depend dramatically upon the nature of N substituents of the chiral controller as well as upon the bulkiness of the ester moiety of the ylide.
- Kanemasa, Shuji,Hayashi, Takeshi,Tanaka, Junji,Yamamoto, Hidetoshi,Sakurai, Tosio
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p. 4473 - 4481
(2007/10/02)
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- IMPROVED OPTICAL RESOLUTION OF R*,R* N,N-DIMETHYL 1,2-DIPHENYL ETHYLENE DIAMINE
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Optically active N,N'-dimethyl 1,2-diphenyl ethylenediamine (DMPEDA) is easily prepared by resolution with tartaric acid.Its e.e. is determined by NMR through imidazolidine formation with (-) myrtenal.
- Mangeney, P.,Grojean, F.,Alexakis, A.,Normant, J. F.
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p. 2675 - 2676
(2007/10/02)
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- Titanium Induced Coupling of Imines to Symmetrical Vicinal (R*,R*)-Diamines
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Symmetrical vicinal (R*,R*) -d,l-diamines were prepared from the corresponding imines and low valent titanium species generated by the action of titanium tetrachloride on amalgamated magnesium.
- Mangeney, P.,Tejero, T.,Alexakis, A.,Grosjean, F.,Normant, J.
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p. 255 - 257
(2007/10/02)
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