81107-71-3Relevant academic research and scientific papers
Asymmetric trisubstituted aziridination of aldimines and ketimines using N-α-Diazoacyl camphorsultams
Hashimoto, Takuya,Nakatsu, Hiroki,Yamamoto, Kumiko,Watanabe, Shogo,Maruoka, Keiji
supporting information; experimental part, p. 607 - 613 (2011/10/12)
The acid-catalyzed reaction of diazoacetates and aldimines (Brookhart-Templeton aziridination) is now recognized as a reliable method to provide enantiomerically enriched disubstituted aziridines, thus owing to the development of asymmetric catalysis. However, the extension of this method to prepare trisubstituted aziridines has not been explored to date, even for racemic products. In this context, and considering their synthetic importance and lack of alternative direct synthetic methods, we recently launched a program to realize this unmet challenge. Herein, we report a detailed study, which led to the establishment of a highly stereoselective synthesis for various trisubstituted aziridines, building on the use of N-α-diazoacyl camphorsultams as a key component. SpringBoc reaction: An acid-catalyzed reaction of N-α-diazoacyl camphorsultams and N-Boc imines has been developed, as a facile means to provide trisubstituted aziridines in a highly stereoselective manner. The use of N-Boc α-ketimino esters and N-α-diazoacetyl camphorsultam as an alternative combination of substrates led to the construction of trisubstituted aziridines with two carbonyl functionalities (see scheme). Copyright
Asymmetric Syntheses via Heterocyclic Intermediates, X. - Enantioselective Synthesis of (2R)-2-Methylserines
Schoellkopf, Ulrich,Groth, Ulrich,Hartwig, Wolfgang
, p. 2407 - 2418 (2007/10/02)
Aldehydes and ketones react with the lithiated bislactim ether 3 of cyclo-(L-Ala-L-Ala) with 81 to >95percent asymmetric induction (d.e. = diastereomeric excess) at C-3; (R) configuration is formed predominantly. - A model concept for the asymmetric induction is proposed. - With aldehydes or unsymmetrical ketones C-7 of the adducts 6 becomes a chiral center, too. (R) configuration is induced here with d. e. 47 - 73percent.Hydrolysis of the addition products 6 (0.25 N HCl, room temperature) gives L-Ala-OCH3 and (2R)-2-methylserine methyl esters 7.Both compounds can be separated either at the ester stage by distillation or - if 7 is thermolabile - after further hydrolysis at the amino acid stage.
