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Asymmetric synthesis of pharmaceutically relevant 1-aryl-2-heteroaryl- and 1,2-diheteroarylcyclopropane-1-carboxylates.

ABSTRACT: This study describes general methods for the enantioselective syntheses of pharmaceutically relevant 1-aryl-2-heteroaryl- and 1,2-diheteroarylcyclopropane-1-carboxylates through dirhodium tetracarboxylate-catalysed asymmetric cyclopropanation of vinyl heterocycles with aryl- or heteroaryldiazoacetates. The reactions are highly diastereoselective and high asymmetric induction could be achieved using either (R)-pantolactone as a chiral auxiliary or chiral dirhodium tetracarboxylate catalysts. For meta- or para-substituted aryl- or heteroaryldiazoacetates the optimum catalyst was Rh₂(R-p-Ph-TPCP)₄. In the case of ortho-substituted aryl- or heteroaryldiazoacetates, the optimum catalyst was Rh₂(R-TPPTTL)₄. For a highly enantioselective reaction with the ortho-substituted substrates, 2-chloropyridine was required as an additive in the presence of either 4 Å molecular sieves or 1,1,1,3,3,3-hexafluoroisopropanol (HFIP). Under the optimized conditions, the cyclopropanation could be conducted in the presence of a variety of heterocycles, such as pyridines, pyrazines, quinolines, indoles, oxadiazoles, thiophenes and pyrazoles.

SUBMITTER: Sharland JC

PROVIDER: S-EPMC8386643 | biostudies-literature | 2021 Aug

REPOSITORIES: biostudies-literature

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Asymmetric synthesis of pharmaceutically relevant 1-aryl-2-heteroaryl- and 1,2-diheteroarylcyclopropane-1-carboxylates.

Sharland Jack C JC Wei Bo B Hardee David J DJ Hodges Timothy R TR Gong Wei W Voight Eric A EA Davies Huw M L HML

Chemical science 20210727 33

This study describes general methods for the enantioselective syntheses of pharmaceutically relevant 1-aryl-2-heteroaryl- and 1,2-diheteroarylcyclopropane-1-carboxylates through dirhodium tetracarboxylate-catalysed asymmetric cyclopropanation of vinyl heterocycles with aryl- or heteroaryldiazoacetates. The reactions are highly diastereoselective and high asymmetric induction could be achieved using either (<i>R</i>)-pantolactone as a chiral auxiliary or chiral dirhodium tetracarboxylate catalyst ...[more]

PMID: 34522315

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Project description: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 heteroaryl 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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Dataset Information

Asymmetric synthesis of pharmaceutically relevant 1-aryl-2-heteroaryl- and 1,2-diheteroarylcyclopropane-1-carboxylates.

Publications

Asymmetric synthesis of pharmaceutically relevant 1-aryl-2-heteroaryl- and 1,2-diheteroarylcyclopropane-1-carboxylates.

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