Triarylborane Ammonia Complexes as Ideal Precursors for Arylzinc Reagents in Asymmetric Catalysis

Dahmen, Stefan; Lormann, Matthias

doi:10.1021/ol0515659

Cited by 66 publications

(20 citation statements)

References 16 publications

(10 reference statements)

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“…Braga demonstrated that the acceleration could be achieved by microwave irradiation 53. Based on Bolm's breakthrough, several aryl boron derivatives, such as triarylboranes42,43,49,54-57 and boroxines,52,58,59 were successfully employed in the asymmetric arylation of aldehydes. It is noteworthy that highly enantioselective late transition metal-based catalysts can also be employed with boronic acid derivatives 60-62…”

Section: Introductionmentioning

confidence: 99%

Practical Catalytic Asymmetric Synthesis of Diaryl-, Aryl Heteroaryl-, and Diheteroarylmethanols

2009

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Enantioenriched diaryl-, aryl heteroaryl-and diheteroarylmethanols exhibit important biological and medicinal properties. One-pot catalytic asymmetric syntheses of these compounds beginning from readily available aryl bromides are introduced. Thus, lithium-bromide exchange with commercially available aryl bromides and n-BuLi was followed by salt metathesis with ZnCl 2 to generate ArZnCl. A second equivalent of n-BuLi was added to form the mixed organozinc, ArZnBu. In the presence of enantioenriched amino alcohol-based catalysts, ArZnBu adds to aldehydes to afford essentially racemic diarylmethanols. The low enantioselectivities were attributed to a LiCl-promoted background reaction. To inhibit this background reaction, the chelating diamine TEEDA (tetraethylethylene diamine) was introduced prior to aldehyde addition. Under these conditions, enantioenriched diarylmethanols were obtained with >90% ee. Arylations of enals generated allylic alcohols with 81-90% ee. This procedure was unsuccessful, however, when applied to heteraryl bromides, which was attributed to decomposition of the heteroaryl lithium under the salt metathesis conditions. To avoid this problem, the metathesis was conducted with EtZnCl, which enabled the salt metathesis to proceed at low temperatures. The resulting EtZn(Ar Hetero ) intermediates (Ar Hetero =2-and 3-thiophenyl, 2-benzothiophenyl, 3-furyl, and 5-indolyl) were successfully added to aldehydes and heteroaryl aldehydes with enantioselectivities between 81-99%. These are the first examples of catalytic and highly enantioselective syntheses of diheteroarylmethanols. In a similar fashion, ferrocenyl bromide was used to generate FcZnEt and the ferrocenyl group added to benzaldehyde and heteroaromatic aldehydes to form ferrocene-based ligand precursors in 86-95% yield with 96-98% ee. It was also found that the arylation and heteroarylation of enals could be followed by diastereoselective epoxidations to provide epoxy alcohols with high enantio-and diastereoselectivities in a one-pot procedure.

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Section: Introductionmentioning

confidence: 99%

Practical Catalytic Asymmetric Synthesis of Diaryl-, Aryl Heteroaryl-, and Diheteroarylmethanols

2009

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“…On the application of 21a, the desired diarylmethanols were isolated with high (up to 98%) ee values. 86 In tests of the enantiomeric induction of 21cee, 22c and 22e in the addition of diethylzinc to arylaldehydes, comparison of the results with the literature data demonstrated that the bulkier naphthylethyl group on the N atom did not cause significantly higher enantioselectivity in the enantioselective alkylation of arylaldehydes. 6 Furthermore, the tertiary aminonaphthols did not improve the ee values significantly.…”

Section: Applications In Enantioselective Transformationsmentioning

confidence: 88%

Syntheses, transformations and applications of aminonaphthol derivatives prepared via modified Mannich reactions

Szatmári

Fülöp

2013

Tetrahedron

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“…sources and have found that triarylborane ammonia complexes are the ideal precursors of the arylzinc reagent for their catalytic system (Scheme 25). 40 In the same way, Chan also described the synthesis of a series of atropisomeric binaphthyl-derived amino alcohols and their application in the catalytic asymmetric phenyl transfer reaction to aromatic and aliphatic aldehydes. 41 The salient features of these chiral amino alcohol ligands include their ease of preparation and the flexibility of modifications on both the binaphthyl moiety and the amino alcohol backbone.…”

Section: Asymmetric Aryl Transfer Reaction With Binol-type Ligandsmentioning

confidence: 97%

Catalytic enantioselective arylations: boron to zinc exchange as a powerful tool for the generation of transferable aryl groups

Paixão¹,

Braga²,

Lüdtke³

2008

J. Braz. Chem. Soc.

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A transmetalação entre boro e zinco apresenta uma grande importância para diversas aplicações em síntese orgânica, uma vez que permite a formação de novas ligações carbono-carbono entre reagentes organometálicos e espécies eletrofílicas. A arilação direta de aldeídos e, mais raramente de cetonas, de maneira catalítica e enantiosseletiva, empregando catalisadores quirais, têm sido descrita recentemente. Os diaril metanóis opticamente enriquecidos, obtidos nessas reações são precursores valiosos para a síntese de moléculas bioativas. O presente trabalho apresenta uma revisão sobre essa crescente área de atuação e destaca alguns dos desafios que ainda permanecem.The transmetalation between boron and zinc is of great importance for application in organic synthesis, since it allows the formation of new carbon-carbon bonds between organometallic units and electrophiles. The direct arylation of aldehydes or more scarcely ketones, in a catalytic, enantioselective manner using chiral catalysts has been described recently. The enantiomerically enriched diarylmethanols obtained in these reactions are valuable precursors for important bioactive molecules. This review provides a synopsis of this ever-growing field and highlights some of the challenges that still remain.

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Triarylborane Ammonia Complexes as Ideal Precursors for Arylzinc Reagents in Asymmetric Catalysis

Cited by 66 publications

References 16 publications

Practical Catalytic Asymmetric Synthesis of Diaryl-, Aryl Heteroaryl-, and Diheteroarylmethanols

Practical Catalytic Asymmetric Synthesis of Diaryl-, Aryl Heteroaryl-, and Diheteroarylmethanols

Syntheses, transformations and applications of aminonaphthol derivatives prepared via modified Mannich reactions

Catalytic enantioselective arylations: boron to zinc exchange as a powerful tool for the generation of transferable aryl groups

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