MyJournals Home  

RSS FeedsProton transfers in the Strecker reaction revealed by DFT calculations (Beilstein Journal of Organic Chemistry)

 
 

1 august 2014 06:34:45

 
Proton transfers in the Strecker reaction revealed by DFT calculations (Beilstein Journal of Organic Chemistry)
 


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 the second stage, the aminonitrile transforms to alanine, where an amide Me-CH(NH2)-C(=O)-NH2 is the key intermediate. The rate-determining step is the hydrolysis of the cyano group of N(amino)-protonated aminonitrile which occurs with an ΔE≠ value of 34.7 kcal/mol. In the Strecker reaction, the proton transfer along the hydrogen bonds plays a crucial role. Beilstein J. Org. Chem. 2014, 10, 1765–1774. doi:10.3762/bjoc.10.184


 
123 viewsCategory: Chemistry
 
Total Synthesis of (±)-Nardoaristolone B and Its Analogues (Organic Letters)
Copper-Catalyzed Direct Trifluoromethylation of Propiolates: Construction of Trifluoromethylated Coumarins (Organic Letters)
 
 
blog comments powered by Disqus


MyJournals.org
The latest issues of all your favorite science journals on one page

Username:
Password:

Register | Retrieve

Search:

Chemistry


Copyright © 2008 - 2024 Indigonet Services B.V.. Contact: Tim Hulsen. Read here our privacy notice.
Other websites of Indigonet Services B.V.: Nieuws Vacatures News Tweets Nachrichten