Proton transfers in the Strecker reaction revealed by DFT calculations.

ABSTRACT: The Strecker reaction of acetaldehyde, NH3, and HCN to afford alanine was studied by DFT calculations for the first time, which involves two reaction stages. In the first reaction stage, the aminonitrile was formed. The rate-determining step is the deprotonation of the NH3 (+) group in MeCH(OH)-NH3 (+) to form 1-aminoethanol, which occurs with an activation energy barrier (ΔE (≠)) of 9.6 kcal/mol. The stereochemistry (R or S) of the aminonitrile product is determined at the NH3 addition step to the carbonyl carbon of the aldehyde. While the addition of CN(-) to the carbon atom of the protonated imine 7 appears to scramble the stereochemistry, the water cluster above the imine plane reinforces the CN(-) to attack the imine group below the plane. The enforcement hinders the scrambling. In th

SUBMITTER: Yamabe S 

PROVIDER: S-EPMC4143099 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature