TY - JOUR
T1 - Thiazolidine Ring Opening in Penicillin Derivatives. Part 2. Enamine Formation
AU - Davis, Andrew M.
AU - Layland, Nicola J.
AU - Page, Michael I.
AU - Martin, Frances
AU - O’ferrall, Rory More
PY - 1991/8
Y1 - 1991/8
N2 - The alkaline hydrolysis of (3S,5R,6R)-methyl benzylpenicilloate, and the corresponding carboxamide and N-ethylamide, is accompanied by an absorbance increase at 285 nm. This is attributed to a competing elimination reaction across C6–C5 to open the thiazolidine ring and reversibly generate an enamine intermediate. Kinetic analysis and hydrolysis in D2O do not indicate a significant buildup of this intermediate during hydrolysis of the methyl ester. However, over the pH range 4–11 the rate of thiazolidine ring opening is competitive with hydrolysis of the ester function. The deuterium solvent kinetic isotope effect on the ring closure reaction is 7.5.
AB - The alkaline hydrolysis of (3S,5R,6R)-methyl benzylpenicilloate, and the corresponding carboxamide and N-ethylamide, is accompanied by an absorbance increase at 285 nm. This is attributed to a competing elimination reaction across C6–C5 to open the thiazolidine ring and reversibly generate an enamine intermediate. Kinetic analysis and hydrolysis in D2O do not indicate a significant buildup of this intermediate during hydrolysis of the methyl ester. However, over the pH range 4–11 the rate of thiazolidine ring opening is competitive with hydrolysis of the ester function. The deuterium solvent kinetic isotope effect on the ring closure reaction is 7.5.
UR - http://www.scopus.com/inward/record.url?scp=0040044725&partnerID=8YFLogxK
U2 - 10.1039/P29910001225
DO - 10.1039/P29910001225
M3 - Article
AN - SCOPUS:0040044725
SP - 1225
EP - 1229
JO - Journal of the Chemical Society, Perkin Transactions 2
JF - Journal of the Chemical Society, Perkin Transactions 2
SN - 0300-922X
IS - 8
ER -