- Nitrile biotransformations for the practical synthesis of highly enantiopure azido carboxylic acids and amides, 'click' to functionalized chiral triazoles and chiral β-amino acids
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Under very mild conditions, biotransformations of racemic azido nitriles using Rhodococcus erythropolis AJ270, a nitrile hydratase/amidase-containing microbial whole-cell catalyst, afforded highly enantiopure, (R)-α-arylmethyl- and (+)-α-cyclohexylmethyl-β-azidopropanoic acids and their (S)- and (-)-carboxamide derivatives in excellent yields. The resulting functionalized chiral organoazides were converted in a straightforward fashion to a pair of antipodes of α-benzyl-β-amino acids (R)-13 and (S)-13. Azido carboxamide (S)-11a and azido carboxylic acid (R)-12a underwent 'click' reactions with diethyl acetylenedicarboxylate and phenylacetylene to produce functionalized chiral triazoles 14 and 15, respectively. The easy preparation of the starting nitrile substrates, highly efficient and enantioselective biotransformation reactions, and versatile utility of the resulting functionalized azido carboxylic acids and amide derivatives, render this method very attractive and practical in organic synthesis.
- Ma, Da-You,Wang, De-Xian,Zheng, Qi-Yu,Wang, Mei-Xiang
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p. 2366 - 2376
(2007/10/03)
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- Unexpected Staudinger reaction of α-azidoacetonitriles α-phenyl substituted with triphenylphospine. Preparation, X-ray crystal and molecular structures of a phosphazine, an aminophosphonium carbanion salt and a phosphazide, with (Z)-configuration
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Staudinger reaction of α-azidophenylacetonitrile with triphenylphosphine in 1:2 molar ratio provides the triphenylphosphazine 4 derived from α-diazophenylacetonitrile, whereas 2:1 molar ratio the final product is found to be the aminotriphenylphosphonium salt of phenylmalononitrile 6. However, the Staudinger reaction of α- azidodiphenylacetonitrile with triphenylphosphine affords the corresponding (Z)-phosphazide 17. The crystal and molecular structures of compounds 4,6, and 17 have been determined by X-ray analysis. Compound 17 is the first isolated phosphazide which presents the (Z)-configuration with respect to the central N,N bond of the PN3C moiety (P-N-N-N= 0.0(3)°).
- Molina, Pedro,Lopez-Leonardo, Carmen,Llamas-Botia, Javier,Foces-Foces, Concepcion,Fernandez-Castano, Cristina
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p. 9629 - 9642
(2007/10/03)
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