Herstellung von α‐Aminosäureestern durch Alkoholyse der Methylester

Brenner, M.; Huber, Walter

doi:10.1002/hlca.19530360522

Cited by 505 publications

(169 citation statements)

References 6 publications

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“…Diethylzinc, (S)--methylbenzylamine (e.e.=99%), aldehydes were purchased from Sigma-Aldrich or Fluka. 3,5-Di-tert-butyl-2-hydroxybenzaldehyde, 3-tert-butyl-5-methyl-2-hydroxybenzaldehyde, 2-hydroxy-3-methylbenzaldehyde and 2-hydroxy-3-isopropylbenzaldehyde were obtained according to literature procedures 42,43 .…”

Section: Discussionmentioning

confidence: 99%

Bidentate Schiff bases derived from (S)-α-methylbenzylamine as chiral ligands in the electronically controlled asymmetric addition of diethylzinc to aldehydes

Jaworska¹,

Wełniak²,

Zięciak³

et al. 2011

Arkivoc

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A group of bidentate Schiff bases derived from enantiomerically pure (S)--methylbenzylamine was synthesized. Crystal structure was determined for three compounds. Schiff bases were used as chiral ligands in the asymmetric addition of Et2Zn to aldehydes. The obtained enantioselectivity was e.e.=8-94% depending on the substrate and the best was observed for (S,E)-2-(1-(1-phenylethylimino)-ethyl)phenol. The enantioselectivity increase was connected with the substituent-induced electronic effects in the substrate molecules. Molecular modeling resulted in the models of the 3D structures of Zn-Zn complex catalysts containing investigated Schiff bases, which were consistent with the reported chirality of the addition product and explained observed e.e. The presented transition state models allow explaining the change of the absolute configuration of diethylzinc addition product in the case of using ortho-substituted aldehydes.

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Section: Discussionmentioning

confidence: 99%

Bidentate Schiff bases derived from (S)-α-methylbenzylamine as chiral ligands in the electronically controlled asymmetric addition of diethylzinc to aldehydes

Jaworska¹,

Wełniak²,

Zięciak³

et al. 2011

Arkivoc

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“…Further transesterification reactions can be found in the literature, in which metal alkoxides [11][12][13][14][15][16] , aluminum isopropoxide [17][18][19] , tetraalkoxytitanium compounds [20][21][22] and organotin alkoxides 23,24 are applied as catalysts.…”

Section: General Aspects Of Transesterificationmentioning

confidence: 99%

Transesterification of vegetable oils: a review

Schuchardt¹,

Sercheli²,

Vargas³

1998

J. Braz. Chem. Soc.

976

539

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A transesterificação de óleos vegetais com metanol, bem como as principais aplicações de ésteres metílicos de ácidos graxos, são revisadas. São descritos os aspectos gerais desse processo e a aplicabilidade de diferentes tipos de catalisadores (ácidos, hidróxidos, alcóxidos e carbonatos de metais alcalinos, enzimas e bases não-iônicas, como aminas, amidinas, guanidinas e triamino(imino)fosforanos). Enfoque especial é dado às guanidinas, que podem ser facilmente heterogeneizadas em polímeros orgânicos. No entanto, as bases ancoradas lixiviam dos polímeros. Novas estratégias para a obtenção de guanidinas heterogeneizadas mais resistentes à lixiviação são propostas. Finalmente, são descritas várias aplicações para ésteres de ácidos graxos, obtidos por transesterificação de óleos vegetais.The transesterification of vegetable oils with methanol as well as the main uses of the fatty acid methyl esters are reviewed. The general aspects of this process and the applicability of different types of catalysts (acids, alkaline metal hydroxides, alkoxides and carbonates, enzymes and non-ionic bases, such as amines, amidines, guanidines and triamino(imino)phosphoranes) are described. Special attention is given to guanidines, which can be easily heterogenized on organic polymers. However, the anchored catalysts show leaching problems. New strategies to obtain non-leaching guanidine-containing catalysts are proposed. Finally, several applications of fatty acid esters, obtained by transesterification of vegetable oils, are described.

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“…11 This protection was made necessary due to the prototropy observed between the carboxylic group and the amino group of the α-amino acids. α-amino esters hydrochlorides were prepared from α-amino acid 1a-d glycine, L-alanine, L-serine and L-proline respectively in EtOH with thionyl chloride as catalyst, with these conditions the protected compounds 2a-d were isolated in excellent yield (Scheme 1).…”

Section: Resultsmentioning

confidence: 99%