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219. Chiral, enantiopure aluminum(III) and titanium(IV) azatranes

Author

Forcato, M., Lake, F., Blazquez, M. M., Renner, P., Crisma, M., Gade, L. H., Licini, G., Moberg, Christina, Forcato, M., Lake, F., Blazquez, M. M., Renner, P., Crisma, M., Gade, L. H., Licini, G., and Moberg, Christina

Abstract

Al-III and Ti-IV complexes of C-3-symmetric tetradentate trisamidoamme ligands with trigonal bipyramidal coordination geometry, containing chlorine or dialkylamido groups, or with a free coordination site in the apical position, have been synthesised by salt metathesis and amine elimination. Products with threefold symmetry were generally obtained for tetravalent titanium, whereas for the aluminium complexes either asymmetric structures with two of the three podand arms taking part in coordination to the metal or symmetric arrangements possessing the full threefold symmetry were formed depending on the steric properties of the ligands., QC 20100525

Published
2006
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229. Exploring new dipeptides based on phenylglycine and C-alpha-methyl phentylglycine as hosts in inclusion resolutions

Author

Muller, S., Ariaans, G.J.A., Kaptein, B., Broxterman, Q.B., Formaggio, F., Battan, E., Crisma, M., Toniolo, C., Bruggink, A., Muller, S., Ariaans, G.J.A., Kaptein, B., Broxterman, Q.B., Formaggio, F., Battan, E., Crisma, M., Toniolo, C., and Bruggink, A.

Abstract

Item does not contain fulltext, Twelve homo-dipeptides derived from phenylglycine, Phg, and C-alpha-methyl phenylglycine, (alphaMe)Phg, were synthesized and tested as resolving agents in resolutions through selective crystallization of inclusion compounds. The 3D-structure of a hydrated (alphaMe)Phg dipeptide host was also solved by single crystal X-ray diffraction. These dipeptides were examined in the co-crystallization with 15 different racemic guests, mainly alcohols and sulfoxides. Next to confirming the literature results for the resolution Of methylphenylsulfoxide. a rather limited scope was found for new resolutions. Only racemic solketal could be resolved with H-(S)-(alphaMe)Phg-(S)-(alphaMe)Phg-OH in modest efficiency using various experimental techniques. This resolution was complicated by the formation of polymorphic host-guest crystals. Whereas a wide array of similar dipeptides could be explored as resolving agents, it is expected to be difficult to rationally design potentially Successful molecular structures. Compared to resolution by diastereomeric salt formation. inclusion complexes are less readily formed and therefore of a more limited scope and preparative applicability. (C) 2004 Elsevier Ltd. All rights reserved.

Published
2004

240. Peptides From Chiral C(alpha,alpha)-disubstituted Glycines - Synthesis and Conformational-analysis of Homochiral (alpha-me) Leu/ala Model Peptides

Author

Kamphuis, J., W. H. J., Schoemaker, H. E., Aubry, A., Bayeul, D., Dautant, A., Pantano, M., Formaggio, Fernando, Crisma, M., Bonora, G. M., and Toniolo, Claudio

Subjects
LINEAR OLIGOPEPTIDES, HYDROGEN-BOND DISTANCES, HYDROGEN-BOND DISTANCES, C-ALPHA, ALPHA-DISUBSTITUTED GLYCINES, STRUCTURAL VERSATILITY, AMINO-ACIDS, PREFERRED CONFORMATION, LINEAR OLIGOPEPTIDES, METHYL, ISOPROPYLGLYCINE, (ALPHA-ME)VAL, HOMOPEPTIDES, STRUCTURAL VERSATILITY, HOMOPEPTIDES, METHYL, ISOPROPYLGLYCINE, AMINO-ACIDS, ALPHA-DISUBSTITUTED GLYCINES, (ALPHA-ME)VAL, PREFERRED CONFORMATION, C-ALPHA
Published
1994

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