Benzyl derivatives center formation

Chiral N-Oxides 250) In the reaction of N-benzyl-N-methylamino amino acids with H202 in alkaline water solution, mixtures of diastereomeric N-oxides, containing new centers of chirality on nitrogen atoms, were obtained. The reaction was performed with the corresponding derivatives of (S)- [or (R)] alanine, (S)- [or (R)] leucine, (S)-[or (R)] phenylalanine, and (S)- [or (R)] proline, respectively. In the reaction a distinct stereoselectivity could be observed for alanine, leucine, and phenylalanine derivatives the formation of N(S)C(S), or correspondingly N C, diastereomer is favoured. The reaction of (S)-proline derivatives leads, however, exclusively to the N(R,C(S) stereoisomer (252) on the other hand, (R)-proline yielded stereoselectively the compound (253). 

It is known that electrochemical reduction of oximes in protic media occurs in two steps the N—O bond is first reduced to form an imine and the latter is then reduced to afford a primary amine1,29. Tallec has shown that the amine from oxime 33 can be trapped intramolecularly (equation 16)35. Interestingly, the SS diastereomer predominates the chiral pyrrolidine ring derivative serves to control the stereochemistry of formation of the new benzylic chiral center. Electrochemical reductive cross-coupling of O-methyl oximes with carbonyl compounds in isopropanol at a tin cathode affords adducts (equation 17) which can be reduced further to 2-amino alcohols36. In this fashion, menthone could... 

Chiral Imidazolidinones with Other Substitution Patterns. The intermediate imidazolidinone (2) can also be N-acylated by Benzoyl Chloride or Benzyl Chloroformate, and other substituents on the acetal center and/or on the N(3) nitrogen can be present, depending upon the aldehyde used for the imine formation and upon the glycine amide employed at the beginning of the synthesis. Chiral substituents, such as the 1-phenylethyl group may be placed on N(3), and the imidazolidinone may be derived from a dipeptide. Some examples are collected for (15), with references, in Table fijesg different derivatives... 

Although considered mild in comparison with other metals, copper(I) and (II) Inflates are suitable Lewis acids for affecting Friedel-Crafts alkylation and acylation reactions (Sch. 22). The intramolecular acylaminoalkylation of the indole derivative 88 afforded the cyclized product 89 in high yield [49]. The nitrogen functionality was not a requirement for formation of the benzylic cation, because the benzylic alcohol 90 reacted similarly with 91, even with an electron-withdrawing ester group adjacent to the cationic center. 

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