Hydrolytic behavior of two β-lactams and their corresponding imidate salts. New evidence for stereoelectronic control

1980 ◽  
Vol 58 (19) ◽  
pp. 2061-2068 ◽  
Author(s):  
Pierre Deslongchamps ◽  
Maurice Caron
Keyword(s):  
Sodium Hydroxide ◽  
Carbonyl Oxygen ◽  
Oxygen Exchange ◽  
Hydrochloride Salt ◽  
Stereoelectronic Control ◽  
Acidic Conditions ◽  
Basic Hydrolysis ◽  
New Evidence ◽  
Hydrolysis Of ◽  
Tetrahedral Intermediates

The basic hydrolysis and the concurrent carbonyl–oxygen exchange of 18O-labelled N-phenyl-4-phenyl-2-azetidinone (5*) and N-2,6-dimethylphenyl-2-azetidinone (6*) have been studied. β-Lactam 5* was easily hydrolysed and showed no carbonyl–oxygen exchange with 0.1 N sodium hydroxide (dioxane–water, 9:1). Under the same conditions, β-lactam 6* gave no exchange and was found resistant to basic hydrolysis. Hydrolysis and exchange was observed when 6* was refluxed with 0.1 N and 1 N sodium hydroxide in water.The hydrolysis of the corresponding imidate salts 7 and 8 was also investigated. Under basic conditions, salt 7 gave an 8:2 mixture of ester amine 9 and β-lactam 5, while under acidic conditions the hydrochloride salt of ester amine 9 was the only product. Under basic conditions, the imidate salt 8 produced only the β-lactam 6, and under acidic conditions, a 3:7 mixture of the hydrochloride salt of 10 and β-lactam 6. Under stronger acidic conditions (≥3 N HCl), 8 gave only the starting β-lactam 6.The results of these hydrolysis reactions are easily explained on the basis of the stereoelectronic theory for the cleavage of tetrahedral intermediates, and by taking into account that the nitrogen of tetrahedral intermediates must be either protonated under acidic conditions, or hydrogen bonded with the solvent under basic conditions in order to observe the cleavage of the C—N bond.

Hydrolysis of cyclic unsymmetrical anti imidate salts. New evidence for stereoelectronic control

1979 ◽  
Vol 57 (24) ◽  
pp. 3262-3271 ◽  
Author(s):  
Pierre Deslongchamps ◽  
Ukken Ouseph Cheriyan ◽  
Roland J. Taillefer
Keyword(s):  
Ammonium Salt ◽  
Controlled Conditions ◽  
Kinetically Controlled ◽  
Stereoelectronic Control ◽  
Acidic Conditions ◽  
New Evidence ◽  
Hydrolysis Of ◽  
Tetrahedral Intermediates ◽  
Hydrogen Bonded

The synthesis and the hydrolytic behavior of the cyclic imidate salts 7, 8, and 9 is reported. Under acidic conditions, the salt 7 gives the ester ammonium salt 21 and the salt 9 gives a 1:1 mixture of the ester ammonium salt 22 and the amide alcohol 23 as the rotamer 23B only. Under basic conditions, the salt 7 (or 8) gives a 2:8 (or 1:9) mixture of the amide alcohol rotamers 25A and 25B (or 27A and 27B) under kinetically controlled conditions. The salt 9 gives, as the kinetic product, the amide alcohol rotamer 23B only. These results can be rationalized on the basis of the stereoelectronic theory for the cleavage of tetrahedral intermediates and by taking into account that the nitrogen in tetrahedral intermediates must be either protonated under acidic conditions, or hydrogen bonded with the solvent under basic conditions, in order to observe the cleavage of a C—N bond.

The products of hydrolysis of cyclic orthoesters as a function of pH and the theory of stereoelectronic control

1985 ◽  
Vol 63 (9) ◽  
pp. 2485-2492 ◽  
Author(s):  
Pierre Deslongchamps ◽  
Jean Lessard ◽  
Yves Nadeau
Keyword(s):  
Acid Hydrolysis ◽  
Hydroxy Ester ◽  
The Other ◽  
Relative Percentage ◽  
Stereoelectronic Control ◽  
Hydrolysis Of ◽  
Tetrahedral Intermediates

The acid hydrolysis of cyclic orthoesters 1, 3–6 (R = Me), and 2 (R = Me and Et) as a function of pH was studied. The bicyclic orthoester 5 yields mainly the hydroxy-ester (less than 5% lactone), and this result is essentially independent of pH. For the other orthoesters, the relative percentage of products differs for each case and varies with pH. At pH ≤ 3, the percentage of lactone is always larger than at pH > 3. These results are explained on the basis of the stereoelectronic theory for the cleavage of tetrahedral intermediates.

ChemInform Abstract: THE HYDROLYSIS OF CYCLIC ORTHOESTERS. STEREOELECTRONIC CONTROL IN THE CLEAVAGE OF HEMIORTHOESTER TETRAHEDRAL INTERMEDIATES

1975 ◽  
Vol 6 (38) ◽  
pp. no-no
Author(s):  
PIERRE DESLONGCHAMPS ◽  
ROBERT CHENEVERT ◽  
ROLAND J. TAILLEFER ◽  
CLAUDE MOREAU ◽  
JOHN K. SAUNDERS
Keyword(s):  
Stereoelectronic Control ◽  
Hydrolysis Of ◽  
Tetrahedral Intermediates

Micellar catalysis of the basic hydrolysis of N-methyl-N-(4'-nitropheny1)-2-phenoxyacetamide. Variation of the magnitude of catalysis for differentsources of hydroxide ions

1981 ◽  
Vol 34 (8) ◽  
pp. 1615 ◽  
Author(s):  
TJ Broxton
Keyword(s):  
Sodium Hydroxide ◽  
Cetyltrimethylammonium Bromide ◽  
Reaction System ◽  
Micellar Catalysis ◽  
Buffer System ◽  
Nucleophilic Catalysis ◽  
Carbonate Ions ◽  
Basic Hydrolysis ◽  
Hydrolysis Of ◽  
Triethylammonium Chloride

The hydrolysis of N-methyl-N-(4'-nitrophenyl)-2-phenoxyacetamide has been studied in the presence and absence of micelles of cetyltrimethylammonium bromide. The micellar catalysis depends on the reaction system being used. Hydrolysis in the presence of sodium hydroxide, and in the presence of borate, carbonate/bicarbonate and triethylamine/triethylammonium chloride buffers has been examined. The magnitude of catalysis is shown to depend on the buffer system used, the concentration of detergent, the concentration of the buffer, the pH and the presence of any added salts. The results confirm that it is unrealistic to compare independent sets of results on different compounds unless the conditions for obtaining those results are identical. ��� Hydrolysis in the presence of carbonate/bicarbonate buffers is shown to be subject to buffer catalysis and, by analogy with results for p-nitrophenyl acetate, nucleophilic catalysis by carbonate ions is suggested.

Hydrolysis and carbonyl-oxygen exchange in tertiary amides. Estimation of the free energy changes for breakdown and conformational changes of tetrahedral intermediates

1980 ◽  
Vol 58 (20) ◽  
pp. 2167-2172 ◽  
Author(s):  
Pierre Deslongchamps ◽  
Roger Barlet ◽  
Roland J. Taillefer
Keyword(s):  
Free Energy ◽  
Conformational Change ◽  
Conformational Changes ◽  
Rate Constants ◽  
Carbonyl Oxygen ◽  
Intermediate Energy ◽  
Second Order ◽  
Oxygen Exchange ◽  
Basic Hydrolysis ◽  
Tertiary Amides

Second order rate constants were measured at several temperatures for the basic hydrolysis and for concurrent carbonyl-oxygen exchange with solvent for N-benzyl-N-methylformamide-18O, N-benzyl-N-methyltrideutéroacetamide-18O, and N-benzyl-N-methyl-α,α-dideuteropropionamide-18O. Carbonyl-oxygen exchange with solvent is rationalized by invoking a conformational change in the tetrahedral intermediate. Energy barriers for these conformational changes are estimated to be of the order of 5.6, 8.0, 8.2 kcal/mol respectively for the above amides.

Sign in / Sign up

Export Citation Format

Share Document