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327
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Mita T, Fukuda N, Roca FX, Kanai M, Shibasaki M. Second Generation Catalytic Asymmetric Synthesis of Tamiflu: Allylic Substitution Route. Org Lett 2006; 9:259-62. [PMID: 17217279 DOI: 10.1021/ol062663c] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Catalytic asymmetric synthesis of Tamiflu, an important antiinfluenza drug, was achieved. After the catalytic enantioselective desymmetrization of meso-aziridine 3 with TMSN3, using a Y catalyst (1 mol %) derived from ligand 2, an allylic oxygen function and C1 unit on the C=C double bond were introduced through cyanophosphorylation of enone and allylic substitution with an oxygen nucleophile. This second generation route of Tamiflu is more practical than our previously reported route. [reaction: see text].
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328
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Suto Y, Kanai M, Shibasaki M. Catalytic Enantioselective Mannich-type Reactions of Ketoimines. J Am Chem Soc 2006; 129:500-1. [PMID: 17227007 DOI: 10.1021/ja068226a] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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329
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Fujimori I, Mita T, Maki K, Shiro M, Sato A, Furusho S, Kanai M, Shibasaki M. Key Role of the Lewis Base Position in Asymmetric Bifunctional Catalysis: Design and Evaluation of a New Ligand for Chiral Polymetallic Catalysts. J Am Chem Soc 2006; 128:16438-9. [PMID: 17177358 DOI: 10.1021/ja067003h] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
New chiral ligands for asymmetric polymetallic catalysts were designed on the basis of the assumption that the higher-order assembly structure is stabilized by modifying the modular unit. The designed ligands 6 and 7 contained a scaffolding cyclohexane ring with a Lewis base phosphine oxide directly attached to the scaffold. A module in the polymetallic complex contains two metals per ligand, and a stable 6-, 5-, 5-membered fused chelation ring system should be generated. Synthesis of these ligands is simple and high yielding, using a catalytic dynamic kinetic resolution promoted by the Trost catalyst as a key step. Ligand function was assessed in a catalytic asymmetric ring-opening reaction of meso-aziridines with TMSCN, a useful reaction for the synthesis of optically active beta-amino acids. The Gd complex generated from Gd(OiPr)3 and the ligand was a highly active and enantioselective catalyst in this reaction. Enantioselectivity was reversed compared to the previously reported d-glucose-derived catalyst containing the same chirality of the individual module. ESI-MS analysis and X-ray crystallographic studies indicate that the assembly state of the modules in the polymetallic catalysts differs depending on the chiral ligand. The difference in the higher-order structure stems from a subtle change (one carbon) in the position of the Lewis base relative to the Gd metal. The change in the higher-order structure of the polymetallic complex led to a dramatic reversal of the enantioselectivity and increased catalyst activity.
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330
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Motoki R, Tomita D, Kanai M, Shibasaki M. Catalytic enantioselective alkenylation and phenylation of trifluoromethyl ketones. Tetrahedron Lett 2006. [DOI: 10.1016/j.tetlet.2006.09.048] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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331
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Zhao D, Oisaki K, Kanai M, Shibasaki M. Dramatic Ligand Effect in Catalytic Asymmetric Reductive Aldol Reaction of Allenic Esters to Ketones. J Am Chem Soc 2006; 128:14440-1. [PMID: 17090010 DOI: 10.1021/ja0652565] [Citation(s) in RCA: 133] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A general catalytic asymmetric reductive aldol reaction of allenic esters to ketones is described. Two distinct constitutional isomers were selectively produced depending on the reaction conditions. A combination of CuOAc/(R)-DTBM-SEGPHOS/PCy3 as the catalyst predominantly produced gamma-cis-products in high yield with excellent enantioselectivity (up to 99% ee). The reaction was applicable to both aromatic and aliphatic ketones, including unsaturated ketones. On the other hand, CuF-Taniaphos complexes produced alpha-aldol products with high diastereo- and enantioselectivity (up to 84% ee). The new Taniaphos derivative L3, containing di(3,5-xylyl)phosphine and morpholine units, produced optimum results in the alpha-selective reaction. The products are versatile chiral building blocks in organic synthesis. Furthermore, the basic reaction pattern (i.e., conjugate addition-aldol reaction) was extended to a catalytic enantioselective alkylative aldol reaction to ketones using dialkylzinc reagents as the initiator.
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332
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Tomita D, Kanai M, Shibasaki M. Nucleophilic Activation of Alkenyl and Aryl Boronates by a Chiral CuIF Complex: Catalytic Enantioselective Alkenylation and Arylation of Aldehydes. Chem Asian J 2006; 1:161-6. [PMID: 17441051 DOI: 10.1002/asia.200600068] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A new method for the catalytic enantioselective alkenylation and arylation of aldehydes involves the activation of alkenyl and aryl boronates by a catalytic amount of the Cu(I)F-DTBM-segphos complex through transmetalation, generating novel alkenyl and aryl copper species. These reagents act as the actual nucleophile. A range of aldehydes can be converted into optically active secondary allyl alcohols or diaryl methanols with excellent enantioselectivity. The appropriate choice of additives, depending on the substrate, is critical to ensure high yields of products. These additives possibly modulate the catalyst turnover step from copper alkoxide intermediates generated by the addition of organocopper reagents to aldehydes.
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333
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Kikuchi N, Kanai M, Kita N, Mitsuhashi Y, Konishi I. Pregnancy complicated with Buerger's disease. Int J Gynaecol Obstet 2006; 94:62-6. [PMID: 16782101 DOI: 10.1016/j.ijgo.2006.03.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2005] [Revised: 03/22/2006] [Accepted: 03/29/2006] [Indexed: 10/24/2022]
Abstract
Buerger's disease is an inflammatory occlusive vascular disorder involving small- and medium-sized arteries in the distal extremities and is usually complicated with thrombophlebitis. Since Buerger's disease develops most frequently in men who smoke, pregnancy complicated with this disease is extremely rare. Only three pregnancies have been reported previously. All cases indicate that Buerger's disease worsens during pregnancy. However, anti-coagulant therapy appeared to be effective in this case. Accordingly, careful observation is mandatory in pregnancies complicated with Buerger's disease.
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334
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Kato N, Mita T, Kanai M, Therrien B, Kawano M, Yamaguchi K, Danjo H, Sei Y, Sato A, Furusho S, Shibasaki M. Assembly State of Catalytic Modules as Chiral Switches in Asymmetric Strecker Amino Acid Synthesis. J Am Chem Soc 2006; 128:6768-9. [PMID: 16719439 DOI: 10.1021/ja060841r] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Self-assembled chiral polymetallic complexes often demonstrate novel properties as asymmetric catalysts. We report the three-dimensional structures of two such asymmetric catalysts (crystals A and B) for Strecker alpha,alpha-disubstituted amino acid synthesis. These complexes are constructed via assembly of the same chiral modules derived from d-glucose, but their assembly modes differ. The enantioselectivity in the Strecker reaction was dramatically switched, depending on which assembly mode was used: the catalyst generated in situ whose structure is represented by crystal B, or by crystal A. These findings provide insight into the functional importance of higher-order structures of an artificial catalyst.
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335
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Wada R, Shibuguchi T, Makino S, Oisaki K, Kanai M, Shibasaki M. Catalytic Enantioselective Allylation of Ketoimines. J Am Chem Soc 2006; 128:7687-91. [PMID: 16756326 DOI: 10.1021/ja061510h] [Citation(s) in RCA: 260] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A general catalytic allylation of simple ketoimines was developed using 1 mol % of CuF.3PPh(3) as catalyst, 1.5 mol % of La(O(i)Pr)(3) as the cocatalyst, and stable and nontoxic allylboronic acid pinacol ester as the nucleophile. This reaction constituted a good template for developing the first catalytic enantioselective allylation of ketoimines. In this case, using LiO(i)Pr as the cocatalyst produced higher enantioselectivity and reactivity than La(O(i)Pr)(3). Thus, using the CuF-cyclopentyl-DuPHOS complex (10 mol %) and LiO(i)Pr (30 mol %) in the presence of (t)BuOH (1 equiv) produced high enantioselectivity up to 93% ee from a range of aromatic ketoimines. Mechanistic studies indicated that LiO(i)Pr accelerates the reaction by increasing the concentration of an active nucleophile, allylcopper.
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336
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Oisaki K, Zhao D, Kanai M, Shibasaki M. Catalytic Enantioselective Aldol Reaction to Ketones. J Am Chem Soc 2006; 128:7164-5. [PMID: 16734461 DOI: 10.1021/ja061815w] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
An enantioselective aldol reaction between ketones and ketene silyl acetals is described using CuF-chiral phosphine as a catalyst. The key for high enantioselectivity was the development of a novel ligand derived from Taniaphos combined with the unique accelerative effect of PhBF3K. These conditions are applicable to various substrates such as aromatic, aliphatic, and heteroaromatic ketones. In the case of substituted nucleophiles, the reaction proceeds well. The diastereoselectivity is independent of ketene silyl acetal geometry. This is the first example of a catalytic enantio- and diastereoselective aldol reaction to ketones using ketene silyl acetals.
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337
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Fukuta Y, Mita T, Fukuda N, Kanai M, Shibasaki M. De Novo Synthesis of Tamiflu via a Catalytic Asymmetric Ring-Opening of meso-Aziridines with TMSN3. J Am Chem Soc 2006; 128:6312-3. [PMID: 16683784 DOI: 10.1021/ja061696k] [Citation(s) in RCA: 264] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
An asymmetric ring-opening reaction of meso-aziridines with TMSN3 was developed using a catalyst prepared from Y(OiPr)3 and chiral ligand 2 in a 1:2 ratio. Excellent enantioselectivity was realized from a wide range of substrates with a practical catalyst loading. The products were efficiently converted to enantiomerically enriched 1,2-diamines, which are versatile chiral building blocks for pharmaceuticals and chiral ligands. This reaction was applied to a catalytic asymmetric synthesis of Tamiflu, a very important anti-influenza drug containing a chiral 1,2-diamino functionality.
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338
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Ma Z, Izumi H, Kanai M, Kabuyama Y, Ahn NG, Fukasawa K. Mortalin controls centrosome duplication via modulating centrosomal localization of p53. Oncogene 2006; 25:5377-90. [PMID: 16619038 DOI: 10.1038/sj.onc.1209543] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Abnormal amplification of centrosomes, commonly found in human cancer, is the major cause of mitotic defects and chromosome instability in cancer cells. Like DNA, centrosomes duplicate once in each cell cycle, hence the defect in the mechanism that ensures centrosome duplication to occur once and only once in each cell cycle results in abnormal amplification of centrosomes and mitotic defects. Centrosomes are non-membranous organelles, and undergo dynamic changes in its constituents during the centrosome duplication cycle. Through a comparative mass spectrometric analysis of unduplicated and duplicated centrosomes, we identified mortalin, a member of heat shock protein family, as a protein that associates preferentially with duplicated centrosomes. Further analysis revealed that mortalin localized to centrosomes in late G1 before centrosome duplication, remained at centrosomes during S and G2, and dissociated from centrosomes during mitosis. Overexpression of mortalin overrides the p53-dependent suppression of centrosome duplication, and mortalin-driven centrosome duplication requires physical interaction between mortalin and p53. Moreover, mortalin promotes dissociation of p53 from centrosomes through physical interaction. The p53 mutant that lacks the ability to bind to mortalin remains at centrosomes, and suppresses centrosome duplication in a transactivation function-independent manner. Thus, our present findings not only identify mortalin as an upstream molecule of p53 but also provide evidence for the involvement of centrosomally localized p53 in the regulation of centrosome duplication.
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339
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Maki K, Motoki R, Fujii K, Kanai M, Kobayashi T, Tamura S, Shibasaki M. Catalyst-controlled asymmetric synthesis of fostriecin and 8-epi-fostriecin. J Am Chem Soc 2006; 127:17111-7. [PMID: 16316259 DOI: 10.1021/ja0562043] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Catalytic asymmetric synthesis of the natural antibiotic fostriecin (CI-920) and its analogue 8-epi-fostriecin and evaluation of their biological activity are described. We used four catalytic asymmetric reactions to construct all of the chiral centers of fostriecin and 8-epi-fostriecin; cyanosilylation of a ketone, Yamamoto allylation, direct aldol reaction, and Noyori reduction, two of which were developed by our group. Catalytic enantioselective cyanosilylation of ketone 13 produced the chiral tetrasubstituted carbon at C-8. Both enantiomers of the product cyanohydrin were obtained with high enantioselectivity by switching the center metal of the catalyst from titanium to gadolinium. Yamamoto allylation constructed the C-5 chiral carbon in the alpha,beta-unsaturated lactone moiety. A direct catalytic asymmetric aldol reaction of an alkynyl ketone using LLB catalyst constructed the chirality at C-9 with the introduction of a synthetically versatile alkyne moiety, which was later converted to cis-vinyl iodide, the substrate for the subsequent Stille coupling for the triene synthesis. Noyori reduction produced the secondary alcohol at C-11 from the acetylene ketone 6 with excellent selectivity. Importantly, all the stereocenters were constructed under catalyst control in this synthesis. This strategy should be useful for rapid synthesis of stereoisomers of fostriecin.
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340
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Zhao D, Oisaki K, Kanai M, Shibasaki M. Catalytic enantioselective intermolecular reductive aldol reaction to ketones. Tetrahedron Lett 2006. [DOI: 10.1016/j.tetlet.2005.12.097] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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341
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Fukuda N, Sasaki K, Sastry TVRS, Kanai M, Shibasaki M. Catalytic Asymmetric Total Synthesis of (+)-Lactacystin. J Org Chem 2006; 71:1220-5. [PMID: 16438540 DOI: 10.1021/jo0524223] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Total synthesis of (+)-lactacystin, a potent and selective proteasome inhibitor, was accomplished using a catalytic enantioselective Strecker reaction of a ketoimine as the initial key step. An enone-derived N-phosphinoyl ketoimine 7 was selected as a stable masked alpha-hydroxy ketoimine analogue. Excellent enantioselectivity (98% ee) and practical catalyst activity were produced under the optimized catalyst preparation method using 2.5 mol % Gd{N(SiMe3)2}3 as a metal source and 3.8 mol % D-glucose-derived ligand 8. This reaction was conducted on a 5 g scale. The chiral tetrasubstituted C-5 carbon efficiently controlled the stereochemistry of the other three chiral centers of lactacystin. Chelation-controlled Meerwein-type reduction of ketone 5 using i-PrMgBr (originally reported by Kang in a related substrate) selectively produced the desired secondary alcohol at the C-9 position. The C-6 hydroxy and C-7 methyl groups were introduced via a silyl conjugate addition followed by the Tamao oxidation and Donohoe methylation, respectively, in a highly stereoselective manner. A practical amount of enantiomerically pure clasto-lactacystin beta-lactone (2), the biologically active form of (+)-lactacystin, can be synthesized using this route. clasto-Lactacystin beta-lactone (2) was converted to (+)-lactacystin following the reported procedure.
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342
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Kuramochi A, Usuda H, Yamatsugu K, Kanai M, Shibasaki M. Total Synthesis of (±)-Garsubellin A. J Am Chem Soc 2005; 127:14200-1. [PMID: 16218611 DOI: 10.1021/ja055301t] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The first total synthesis of garsubellin A, a neurotrophic compound with potent choline acetyltransferase-inducing activity, is described. Keys for success were (1) stereoselective intermolecular aldol reaction at the C-4 position with acetaldehyde, (2) stereoelective Claisen rearrangement to introduce an allyl group to the most sterically crowded position at C-6, (3) ring-closing metathesis to construct the B-ring, and (4) Wacker-type oxidative C-ring formation. This synthetic route can be extended to an asymmetric synthesis of garsubellin A using the Koga catalytic enantioselective alkylation, which produced enantioenriched alpha-prenyl cyclohexenone with excellent enantioselectivity (95% ee).
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343
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Mita T, Fujimori I, Wada R, Wen J, Kanai M, Shibasaki M. Catalytic Enantioselective Desymmetrization of meso-N-Acylaziridines with TMSCN. J Am Chem Soc 2005; 127:11252-3. [PMID: 16089448 DOI: 10.1021/ja053486y] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A catalytic enantioselective desymmetrization of meso-N-p-nitrobenzoylaziridines with TMSCN was developed using a chiral gadolinium catalyst generated from Gd(OiPr)3 and d-glucose-derived ligand 1. In this reaction, the addition of a catalytic amount of trifluoroacetic acid (TFA) improved enantioselectivity. High enantioselectivity was obtained from a range of meso-aziridines at 0-60 degrees C. The product could be easily transformed into beta-amino acids. Thus, the developed catalytic enantioselective desymmetrization reaction allowed for efficient catalytic synthesis of chiral cyclic beta-amino acids. The incorporation of TFA into the catalyst complex was observed using ESI-MS. Generation of this new complex might be the origin of the improved enantioselectivity.
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344
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Suto Y, Tsuji R, Kanai M, Shibasaki M. Cu(I)-Catalyzed Direct Enantioselective Cross Aldol-Type Reaction of Acetonitrile. Org Lett 2005; 7:3757-60. [PMID: 16092868 DOI: 10.1021/ol051423e] [Citation(s) in RCA: 154] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Direct catalytic enantioselective cross aldol-type reaction of an acetate surrogate was developed using Cu alkoxide-chiral phosphine complexes as catalysts. Chemoselective activation and deprotonation of the donor substrate (acetonitrile) by the soft metal alkoxide in a strongly donating solvent (HMPA) are key to success in this reaction. Useful chemical yields and promising enantioselectivities are produced using either DTBM-SEGPHOS or a tuned BIPHEP as a chiral ligand. [reaction: see text]
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345
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Suzuki M, Kato N, Kanai M, Shibasaki M. Catalytic enantioselective synthesis of key intermediates for triazole antifungal agents. Org Lett 2005. [PMID: 15957882 DOI: 10.1021/ol050398] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
[reaction: see text] A short-step synthesis of versatile chiral building blocks for triazole antifungal agents such as ZD0870 and Sch45450 was developed via catalytic enantioselective cyanosilylation of electron-deficient ketones as the key step. High enantioselectivity was produced using a catalyst prepared from Gd(HMDS)(3) and ligand 5 in a 2:3 ratio. This new catalyst preparation method was superior to the previous method using Gd(O(i)Pr)(3) as a metal source. A rationale for the difference is proposed on the basis of structural studies of the catalyst complexes using ESI-MS.
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346
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Suzuki M, Kato N, Kanai M, Shibasaki M. Catalytic Enantioselective Synthesis of Key Intermediates for Triazole Antifungal Agents. Org Lett 2005; 7:2527-30. [PMID: 15957882 DOI: 10.1021/ol050398+] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
[reaction: see text] A short-step synthesis of versatile chiral building blocks for triazole antifungal agents such as ZD0870 and Sch45450 was developed via catalytic enantioselective cyanosilylation of electron-deficient ketones as the key step. High enantioselectivity was produced using a catalyst prepared from Gd(HMDS)(3) and ligand 5 in a 2:3 ratio. This new catalyst preparation method was superior to the previous method using Gd(O(i)Pr)(3) as a metal source. A rationale for the difference is proposed on the basis of structural studies of the catalyst complexes using ESI-MS.
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347
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Kanai M, Shibasaki M, Kato N, Ichikawa E. Power of Cooperativity: Lewis Acid-Lewis Base Bifunctional Asymmetric Catalysis. Synlett 2005. [DOI: 10.1055/s-2005-869831] [Citation(s) in RCA: 277] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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348
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Ichikawa E, Suzuki M, Yabu K, Albert M, Kanai M, Shibasaki M. New entries in Lewis acid-Lewis base bifunctional asymmetric catalyst: catalytic enantioselective Reissert reaction of pyridine derivatives. J Am Chem Soc 2005; 126:11808-9. [PMID: 15382912 DOI: 10.1021/ja045966f] [Citation(s) in RCA: 174] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The first catalytic enantioselective Reissert reaction of pyridine derivatives that affords products with excellent regio- and enantioselectivity is described. The key for success is the development of new Lewis acid-Lewis base bifunctional asymmetric catalysts containing an aluminum as a Lewis acid and sulfoxides or phosphine sulfides as a Lewis base. These reactions are useful for the synthesis of a variety of chiral piperidine subunits, and catalytic enantioselective formal synthesis of CP-293,019, a selective D4 receptor antagonist, was achieved. Preliminary mechanistic studies indicated that both sulfoxides and phosphine sulfides can activate TMSCN as a Lewis base. In addition, the sulfoxides with appropriate stereochemistry might stabilize a highly enantioselective bimetallic complex (a presumed active catalyst) through internal coordination to aluminum.
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349
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Mita T, Sasaki K, Kanai M, Shibasaki M. Catalytic enantioselective conjugate addition of cyanide to alpha,beta-unsaturated N-acylpyrroles. J Am Chem Soc 2005; 127:514-5. [PMID: 15643862 DOI: 10.1021/ja043424s] [Citation(s) in RCA: 135] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A catalytic enantioselective conjugate addition of cyanide to alpha,beta-unsaturated N-acylpyrroles was developed using the chiral gadolinium catalyst generated from Gd(OiPr)3 and d-glucose-derived ligand 2. Generally high enantioselectivity was obtained from a wide range of substrates; substrates with beta-aryl and beta-vinyl substituents and alpha,beta-disubstituted substrates can now be used. Using this reaction as a key step, short-step syntheses of several pharmaceuticals and their lead compounds were achieved, including the beta-phenyl-substituted GABA analogue and pregabalin.
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350
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Tomita D, Wada R, Kanai M, Shibasaki M. Enantioselective Alkenylation and Phenylation Catalyzed by a Chiral CuF Complex. J Am Chem Soc 2005; 127:4138-9. [PMID: 15783173 DOI: 10.1021/ja0507362] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A new method for CuF-catalyzed alkenylation and phenylation of aldehydes and an activated ketone using air- and moisture-stable alkenylsilanes and phenylsilane as a nucleophile is described. This methodology was extended to highly enantioselective catalytic alkenylation and phenylation using DTBM-SEGPHOS as a chiral ligand. Substrate generality is broad, and an alkenylsilane with a long alkyl chain and an internal alkenylsilane can be also used as a nucleophile. The key to success partly involves the accelerated regeneration of reactive alkenylcopper and phenylcopper through transmetalation from the silylated nucleophiles, and stabilization of the reactive copper reagents, both of which are effected by the diphosphine ligands.
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