128257-10-3Relevant articles and documents
Enzyme-catalyzed enantiomeric resolution of N-Boc-proline as the key-step in an expeditious route towards RAMP
Kurokawa, Masayuki,Shindo, Takeyuki,Suzuki, Masumi,Nakajima, Nobuyoshi,Ishihara, Kohji,Sugai, Takeshi
, p. 1323 - 1333 (2007/10/03)
For the preparation of both enantiomers of N-carbamoyl-2-methoxymethylpyrrolidine, the precursors of Enders' chiral auxiliaries, SAMP and RAMP, enzyme-catalyzed kinetic resolution of racemic N-carbamoyl, N-Boc, N-Cbz proline esters and prolinols were examined. B. licheniformis protease (subtilisin) preferentially hydrolyzed the (R)-carbamoylproline ester with an enantiomeric ratio (E) of 10. To a hydrophobic N-Cbz proline ester, subtilisin showed lower selectivity (E=2.8), and in contrast, a purified protease (isozyme A) from the earthworm showed the preference of (S)-enantiomer (E=13.6). In a practical sense, C. antarctica lipase B (Chirazyme L-2) was effective for the hydrolysis of both N-Boc and N-Cbz derivatives with E >100. The e.e. of (R)-N-carbamoyl-2-methoxymethylpyrrolidine was raised to be >99.9% by recrystallization at the N-Boc-prolinol stage, which was derived from the (R)-N-Boc-proline methyl ester (98.7% e.e.) through a preparative-scale enzyme-catalyzed resolution (49% yield) of the racemic substrate.
Asymmetric induction by chiral heterocyclic compounds: highly diastereoselective reaction of 5-oxa-7,8a-diazaperhydroazulen-8-ones with organometallic reagents
Takahashi, Hiroshi,Morimoto, Ichiro,Higashiyama, Kimio
, p. 287 - 290 (2007/10/02)
1) New chiral heterocyclic compounds, 5-oxa-7,8a-diazaperhydroazulen-8-ones (3a-c), were synthesized from (S)-prolinol (1) and potassium cyanate, followed by the condensation with aldehydes. 2) Extremely high diastereoselective reaction of the 3a-c with diethylzinc proceeded with a facil procedure to give (2S,1'S)-N-1'-arylpropyl-2-hydroxymethyl-1-pyrrolidinecarboxamide (4a-c). 3) The reduction of 4a-c with Red-Al gave (S)-1-aryl-N-methylpropylamines (5a-c) and (S)-prolinol (1) in good yields.