Direkte katalytische asymmetrische Reaktionen unter Protonentransferkatalyse

Kumagai, Naoya; Shibasaki, Masakatsu

doi:10.1002/ange.201100918

Cited by 70 publications

(3 citation statements)

References 228 publications

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“…The direct catalytic reaction between an enolizable carbonyl compound and an electrophile under proton-transfer conditions has emerged as a challenging versatile transformation in organic synthesis. [1] Over the last years several chiral Brønsted bases have been developed to promote this transformation diastereo-and enantioselectively. [2] However, successful examples are mostly limited to 1,3-dicarbonyl compounds and acidic carbon analogues as the pronucleophilic reaction partners.…”

Section: Dedicated To Professor Carmen Nµjeramentioning

confidence: 99%

Catalytic Enantioselective Synthesis of Tertiary Thiols From 5H‐Thiazol‐4‐ones and Nitroolefins: Bifunctional Ureidopeptide‐Based Brønsted Base Catalysis

et al. 2013

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The direct catalytic reaction between an enolizable carbonyl compound and an electrophile under proton-transfer conditions has emerged as a challenging versatile transformation in organic synthesis.[1] Over the last years several chiral Brønsted bases have been developed to promote this transformation diastereo-and enantioselectively.[2] However, successful examples are mostly limited to 1,3-dicarbonyl compounds and acidic carbon analogues as the pronucleophilic reaction partners. 5H-Thiazol-4-ones, in contrast, have been well known for a long time and have found several applications in pharmaceutical and medicinal chemistry.[3] Although structurally related to 5H-oxazol-4-ones [4] and 4H-oxazol-5-ones (azlactones), [5] 5H-thiazol-4-ones have, as far as we know, been never been used in asymmetric synthesis in spite of the fact that they may be easily deprotonated [6] and in spite of the importance of thiols and organosulfur compounds in organic synthesis [7] and chemical biology. [8] In this context, whilst chiral secondary thiol derivatives have been the subject of most investigations, tertiary thiols have remained mostly unexplored owing to the insufficient catalytic enantioselective methodology for their preparation in optically pure form. [9] The most general synthesis of organosulfur compounds involves reaction of a sulfur nucleophile with an electrondeficient p-olefin acceptor.[10] By using this approach Zhang and co-workers [11] reported an efficient catalytic asymmetric synthesis of tertiary thiols using chiral Brønsted bases and bsubstituted b-ethoxycarbonyl nitroalkene acceptors. Conversely, tertiary thiols may be produced through conjugate additions of sulfur-based carbon pronucleophiles.[12] For instance, using rhodanines as carbon pronucleophiles and iminium catalysis, Ye and co-workers [13] have recently reported the conjugate addition and the Diels-Alder reaction to a,b-unsaturated ketones and 2,4-dienals, respectively. Tertiary thiols have also been accessed through enantioselective a-sulfenylation of aldehydes, [14a] 1,3-dicarbonyl compounds, [14b] b-keto phosphonates, [14c] and 3-substituted oxindoles.[14d-g] Other methods include thiofunctionalization of unactivated alkenes,[15a] amination of 3-thiooxindoles, [15b] and the aldol [15c] and Mannich [15d] reactions of a-sulfanyl lactones. Accordingly, whilst many methodologies for the enantioselective synthesis of secondary thiols exist, approaches for the asymmetric synthesis of tertiary thiols are clearly necessary to help fill this important gap in organic chemistry. The inherent difficulty associated with the stereoselective construction of quaternary stereogenic centers is probably the reason for the limited number of studies. [16] In connection with our efforts directed towards the asymmetric synthesis of organosulfur compounds, that is, b,b-disubstituted b-mercapto carboxylic acids [17a,b] and thiiranes, [17c] we focused on the enantioselective generation of a tetrasubstituted carbon atom at the a position of a-mercapto carboxylic ...

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Section: Dedicated To Professor Carmen Nµjeramentioning

confidence: 99%

Catalytic Enantioselective Synthesis of Tertiary Thiols From 5H‐Thiazol‐4‐ones and Nitroolefins: Bifunctional Ureidopeptide‐Based Brønsted Base Catalysis

et al. 2013

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“…Current interest in organocatalysis has focused much attention on the development of chiral Brønsted bases (BBs) to catalyse proton-transfer reactions for the production of optically enriched products. [1] In particular, catalysts that combine a site with BB character and another site with hydrogen-bond donor ability have emerged as the most powerful tools to achieve this goal. [2] Remarkable advances in this context have been made since the first chiral thiourea-tertiary amine catalyst A, developed by Takemoto [3] (Figure 1).…”

Section: Introductionmentioning

confidence: 99%

Ureidopeptide‐Based Brønsted Bases: Design, Synthesis and Application to the Catalytic Enantioselective Synthesis of β‐Amino Nitriles from (Arylsulfonyl)acetonitriles

Diosdado

López

Palomo

2014

Chemistry A European J

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The addition of cyanoalkyl moieties to imines is a very attractive method for the preparation of β-amino nitriles. We present a highly efficient organocatalytic methodology for the stereoselective synthesis of β-amino nitriles, in which the key to success is the use of ureidopeptide-based Brønsted base catalysts in combination with (arylsulfonyl)acetonitriles as synthetic equivalents of the acetonitrile anion. The method gives access to a variety of β-amino nitriles with good yields and excellent enantioselectivities, and broadens the stereoselective Mannich-type methodologies available for their synthesis.

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“…Truly efficient synthetic methodsr equire sustainable actions, [18] as firmly requested by Trost and Sheldon, [19] Noyori, [20] and very recently by Anastas and Zimmerman. [21] In this regard, we also would like to highlight that our synthetic methodc omplies with the well-known3 Rs principles to reduce environmental impact, namely reduction (of steps), recycling (of materials), and reuse (of reagents).…”

mentioning

confidence: 98%

Towards Enzyme‐like, Sustainable Catalysis: Switchable, Highly Efficient Asymmetric Synthesis of Enantiopure Biginelli Dihydropyrimidinones or Hexahydropyrimidinones

Lillo

Saá

2016

Chemistry A European J

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Organocatalysts displaying a network of cooperative hydrogen bonds (NCHB) have been employed in an enzyme-like manner for a direct, switchable synthesis of enantiopure hexahydropyrimidinones (HHPMs) or dihydropyrimidinones (DHPMs), which starts at a common, easily accessible α-ureidosulfone stage. The NCHB organocatalyst exploits all its potential as a pure hydrogen-bond biomimetic catalyst even in the presence of organic bases. This one-pot, diastereo- and enantioselective synthetic procedure has been proven to be robust, scalable, highly efficient, and environmentally benign. A straightforward and truly practical entry to enantiopure HHPMs is reported for the first time.

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Direkte katalytische asymmetrische Reaktionen unter Protonentransferkatalyse

Cited by 70 publications

References 228 publications

Catalytic Enantioselective Synthesis of Tertiary Thiols From 5H‐Thiazol‐4‐ones and Nitroolefins: Bifunctional Ureidopeptide‐Based Brønsted Base Catalysis

Catalytic Enantioselective Synthesis of Tertiary Thiols From 5H‐Thiazol‐4‐ones and Nitroolefins: Bifunctional Ureidopeptide‐Based Brønsted Base Catalysis

Ureidopeptide‐Based Brønsted Bases: Design, Synthesis and Application to the Catalytic Enantioselective Synthesis of β‐Amino Nitriles from (Arylsulfonyl)acetonitriles

Towards Enzyme‐like, Sustainable Catalysis: Switchable, Highly Efficient Asymmetric Synthesis of Enantiopure Biginelli Dihydropyrimidinones or Hexahydropyrimidinones

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