On the Way to α-Methyl-α-amino Acids; Unusual Elimination-addition in 3,3-Disubstituted 1,4-Benzodiazepin-2-ones and Inversion of Enantioselectivity in the Lipase Catalyzed AcetylationReportar como inadecuado




On the Way to α-Methyl-α-amino Acids; Unusual Elimination-addition in 3,3-Disubstituted 1,4-Benzodiazepin-2-ones and Inversion of Enantioselectivity in the Lipase Catalyzed Acetylation - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

Croatica Chemica Acta, Vol.73 No.3 September 2000. -

−-3 -Methanesulfoxymethyl-3-acetoxoymethyl-7-chloro-5-phenyl-1,4-benzodiazepin-2-one, −-2, reacts with ethanethiol in the presence of a strong base affording racemic elimination-addition product 3-ethylthiomethyl-7-chloro-5-phenyl-1,4-benzodiazepin-2-one 4. In-termediary 3-methylene-7-chloro-5-phenyl-1,4-benzodiazepin-2-one 3 is formed by pericyclic C−C bond breaking during elimination of both acyloxy groups. The second approach to α-methyl-α-amino acids comprises kinetic resolution of racemic 3-hydroxymethyl-3-benzyl-7-chloro-5-phenyl-1,4-benzodiazepin-2-one 7 via acetylation by Novozym 435 lipase; enantiomeric excess e.e. for alcohol 3S-+-7 33.2%; e.e. for acetate 3R-−-8 30.2%. Opposite direction of enantio-selectivity during acetylation of 7 and the recently studied 9 Ref. 3 was established by determination of absolute conformation and rela-tive configuration at C3 pseudoaxial-pseudoequatorial by com-bining CD and 1H NMR spectroscopy.

1,4-Benzodiazepin-2-ones; kinetic resolution; absolute configuration



Autor: Amir Avdagić - ; Ruđer Bošković Institute, P. O. Box 180, Bijenička 54, HR-10002 Zagreb, Croatia Vitomir Šunjić - ; Ruđer

Fuente: http://hrcak.srce.hr/



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