A Bench-Stable Homodinuclear Ni<sub>2</sub>−Schiff Base Complex for Catalytic Asymmetric Synthesis of α-Tetrasubstituted <i>anti</i>-α,β-Diamino Acid Surrogates

Chen, Zhihua; Morimoto, Hiroyuki; Matsunaga, Shigeki; Shibasaki, Masakatsu

doi:10.1021/ja710398q

Cited by 303 publications

(129 citation statements)

References 13 publications

(14 reference statements)

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“…After some experimentation, we could identify the use of NiCl 2 ·6 H 2 O and NaBH 4 in EtOH at 0 8C as the optimal set of parameters for reduction of the nitro www.chemeurj.org group, which furnished the target aminoalcohol in 91 % yield. [43] The resulting amine, in turn, was elaborated into the first guanidine moiety using N,N'-bisA C H T U N G T R E N N U N G (Boc)-S-methylisothiourea, HgCl 2 , and triethylamine (80 %). Oxidation of the exocyclic secondary hydroxyl function in 68 with DessMartin periodinane (70 %) [42] was followed by hydrogenolytic cleavage of the benzyl carbamate and guanidinylation of the free amine 69 by repeating the protocol described above furnishing diguanidine 70 in 75 % over two steps.…”

Section: Resultsmentioning

confidence: 99%

Towards the Synthesis of Massadine: A Unified Strategy for the Stereoselective Synthesis of the Carbocyclic C,D‐Ring Subunit

Breder¹,

Chinigo²,

Waltman³

et al. 2011

Chemistry A European J

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Massadine is a hexacyclic marine natural product, which belongs to the family of pyrrole-imidazole alkaloids. Herein, we describe a unified approach to the C,D-ring subunit of this sponge metabolite based on the exploitation of a norbornene scaffold for the stereocontrolled construction of massadine's carbon skeleton. Highlights of the sequence presented include the application of a stereospecific norbornyl rearrangement for facile introduction of an oxygen at the C7-position within the norbornene nucleus, a highly regioselective and end group differentiating ozonolytic scission of a C-C double bond, and an oxidative decarboxylation reaction for the installation of the hindered secondary C2-alcohol function. Furthermore, the iterative assembly of the two guanidine entities as well as the implementation of the spirocyclic junction between the C- and the D-rings are described. Collectively, these key transformations permit an entry to an appropriately functionalized carbon framework, which will serve as a starting point for our efforts toward the completion of the synthesis of massadine.

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Section: Resultsmentioning

confidence: 99%

Towards the Synthesis of Massadine: A Unified Strategy for the Stereoselective Synthesis of the Carbocyclic C,D‐Ring Subunit

Breder¹,

Chinigo²,

Waltman³

et al. 2011

Chemistry A European J

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“…Mannich-type reactions of aryl, heteroaryl, and isomerizable alkyl N-Boc imines and a-substituted nitroacetates gave products in 91% to >99% ee and high antiselectivity (Scheme 4) [22], which were successfully converted into a,b-diamino acids with a-tetrasubstituted stereocenter. Catalyst loading was successfully 0°C to rt, 3 h 94 % yield 98 % ee Scheme 4 Ni 2 -1b-catalyzed direct asymmetric Mannich-type reaction of a-nitroacetates and transformation to a,b-diamino acid with a-tetrasubstituted stereocenter reduced to 1 mol%, while maintaining high enantioselectivity.…”

Section: Lewis Acid/lewis Acid Heterobimetallic Schiff Base Catalystmentioning

confidence: 99%

“…8, the Ni 2 -1b complex was applicable to broad range of catalytic asymmetric reactions under simple proton transfer conditions [19][20][21][22][23][24][25][26][27][28][29][30]. As donors in direct Mannich-type reactions, not only a-nitroacetates, but also malonates, b-keto esters [22], b-keto phosphonates [23], and a-ketoanilides [24] gave excellent enantioselectivity and diastereoselectivity. It is noteworthy that the Ni 2 -1b complex also promoted vinylogous direct catalytic asymmetric Mannichtype reaction of an a,b-unsaturated g-butyrolactam, giving synthetically versatile functionalized a,b-unsaturated g-butyrolactam in 99% ee [25].…”

Section: Lewis Acid/lewis Acid Heterobimetallic Schiff Base Catalystmentioning

confidence: 99%

Multimetallic Multifunctional Catalysts for Asymmetric Reactions

Shibasaki

Kanai

Matsunaga

et al. 2011

Bifunctional Molecular Catalysis

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The utility of several types of multimetallic asymmetric catalysts is reviewed. The appropriate design of multidentate chiral ligands provides homobimetallic, heterobimetallic, and polymetallic catalysts upon complexation with metal cations. Cooperative work of multiple catalytically active sites in the asymmetric multimetallic catalysts allows for enhanced catalytic activity and stereoselectivity over monometallic catalysts. Facile systematic tuning of the asymmetric multimetallic catalysts by manipulation of multidentate ligand structure and combination of metal cations enables the generation of diverse set of catalysts having distinct three-dimensional and catalytic properties, boosting the optimization process to identify the best catalyst for a specific reaction of interest.

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“…When we began this project, there were several precedents for the catalytic asymmetric Mannich-type reaction using 1,3-dicarbonyl compounds as pronucleophiles generating quaternary stereogenic centers with 1,2-syn relative stereochemistry. [74][75][76][77][78][79] None of these examples, however, exhibited high anti-diastereoselectivity. In contrast to 1,3-dicarbonyl compounds, which coordinate to metal-based catalysts in a bidentate fashion, acyanoketones display a monodentate coordination mode, where it is difficult to control the stereochemical course of (Table 4).…”

Section: Catalytic Asymmetric Amination Of Succinimide Derivatives mentioning

confidence: 99%

Development of Atom-Economical Catalytic Asymmetric Reactions under Proton Transfer Conditions: Construction of Tetrasubstituted Stereogenic Centers and Their Application to Therapeutics

Kumagai

2011

CHEMICAL & PHARMACEUTICAL BULLETIN

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The development of atom-economical catalytic asymmetric reactions based on two distinct sets of catalyst, a rare earth metal/amide-based ligand catalyst and a soft Lewis acid/hard Brønsted base catalyst, is reviewed. These catalytic systems exhibit high catalytic activity and stereoselectivity by harnessing a cooperative catalysis through hydrogen bond/metal coordination and soft-soft interactions/hard-hard interactions, respectively. The effectiveness of these cooperative catalysts is clearly delineated by the high stereoselectivity in reactions with highly coordinative substrates, and the specific activation of otherwise low-reactive pronucleophiles under proton transfer conditions. The rare earth metal/amide-based ligand catalyst was successfully applied to catalytic asymmetric aminations, nitroaldol (Henry) reactions, Mannich-type reactions, and conjugate addition reactions, generating stereogenic tetrasubstituted centers. Catalytic asymmetric amination and anti-selective catalytic asymmetric nitroaldol reactions were successfully applied to the efficient enantioselective synthesis of therapeutic candidates, such as AS-3201 and the b b 3 -adrenoreceptor agonist, showcasing the practical utility of the present protocols. The soft Lewis acid/hard Brønsted base cooperative catalyst was specifically developed for the chemoselective activation of soft Lewis basic allylic cyanides and thioamides, which are otherwise low-reactive pronucleophiles. The cooperative action of the catalyst allowed for efficient catalytic generation of active carbon nucleophiles in situ, which were integrated into subsequent enantioselective additions to carbonyl-type electrophiles.

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A Bench-Stable Homodinuclear Ni₂−Schiff Base Complex for Catalytic Asymmetric Synthesis of α-Tetrasubstituted anti-α,β-Diamino Acid Surrogates

Cited by 303 publications

References 13 publications

Towards the Synthesis of Massadine: A Unified Strategy for the Stereoselective Synthesis of the Carbocyclic C,D‐Ring Subunit

Towards the Synthesis of Massadine: A Unified Strategy for the Stereoselective Synthesis of the Carbocyclic C,D‐Ring Subunit

Multimetallic Multifunctional Catalysts for Asymmetric Reactions

Development of Atom-Economical Catalytic Asymmetric Reactions under Proton Transfer Conditions: Construction of Tetrasubstituted Stereogenic Centers and Their Application to Therapeutics

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A Bench-Stable Homodinuclear Ni2−Schiff Base Complex for Catalytic Asymmetric Synthesis of α-Tetrasubstituted anti-α,β-Diamino Acid Surrogates

Cited by 303 publications

References 13 publications

Towards the Synthesis of Massadine: A Unified Strategy for the Stereoselective Synthesis of the Carbocyclic C,D‐Ring Subunit

Towards the Synthesis of Massadine: A Unified Strategy for the Stereoselective Synthesis of the Carbocyclic C,D‐Ring Subunit

Multimetallic Multifunctional Catalysts for Asymmetric Reactions

Development of Atom-Economical Catalytic Asymmetric Reactions under Proton Transfer Conditions: Construction of Tetrasubstituted Stereogenic Centers and Their Application to Therapeutics

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A Bench-Stable Homodinuclear Ni₂−Schiff Base Complex for Catalytic Asymmetric Synthesis of α-Tetrasubstituted anti-α,β-Diamino Acid Surrogates