930-21-2Relevant articles and documents
AN EFFICIENT β-AMINO ACID CYCLODEHYDRATION USING METHANESULFONYL CHLORIDE TO THIENAMYCIN INTERMEDIATE 3--4--AZETIDIN-2-ONE
Loewe, M. F.,Cvetovich, R. J.,Hazen, G. G.
, p. 2299 - 2302 (1991)
A new process for β-amino acid 1 cyclodehydration to β-lactam 2 using methanesulfonyl chloride/ sodium bicarbonate is described.
Method for synthesizing 2-azetidinone
-
Paragraph 0019-0028; 0029-0038; 0039-0048, (2018/06/26)
The invention discloses a method for synthesizing 2-azetidinone in the technical field of chemical synthesis. The method comprises specific steps as follows: S1, preparation of a mixed solution; S2, addition of an aid and dilution; S3, solution extraction and drying; S4, addition of sodium hydroxide and heating; S5, solution neutralization, water washing and drying; S6, toluene dissolution; S7, detection with a chromatograph; S8, product purification treatment. The synthesis method is simple, the prepared finished product has high accuracy, the temperature and the reaction time are controllable in the synthesis process, no raw material waste phenomenon is caused in the synthesis process and the method is suitable for large-scale production in a factory.
Synthesis of lactams using enzyme-catalyzed aminolysis
Stavila,Loos
, p. 370 - 372 (2013/02/25)
The formation of caprolactam from 6-aminocaproic acid catalyzed by CALB (N435) is reported. Different lactam ring sizes can be prepared starting from 4-aminobutanoic acid, 5-aminovaleric acid, and 8-aminooctanoic acid. Experiments with mixtures of aminocarboxylic acids have shown that CALB prefers homocyclization of the individual aminocarboxylic acids.
Suppressed β-effect of silicon in 3-silylated monocyclic β-lactams: The role of antiaromaticity
Bag, Subhendu Sekhar,Kundu, Rajen,Basak, Amit,Slanina, Zdenek
supporting information; experimental part, p. 5722 - 5725 (2010/03/01)
[Chemical Equation Presented] The β-stabilizing effect of silicon substituent at C-3 on a C-4 cation and a radical In the 2-azetidinone systems is studied using NMR kinetics. While the β-effect Is virtually nonexistent in the case of a cation, a foiled β-effect (only a 3-fold rate enhancement) Is observed for a radical intermediate. From both the experimental and theoretical studies, It Is demonstrated that antiaromaticity Is playing the prime role In suppressing the β-stabilizing effect of silicon.
Use of 2,2′-dibenzothiazolyl disulfide-triphenylphosphine and Lawesson's Reagent in the cyclization of β-amino acids
Kanwar, Seema,Sharma
, p. 1748 - 1752 (2007/10/03)
The disulfide reagents 2,2′-dithiobisbenzothiazole (MBTS) and 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide (Lawesson's Reagent, LR) mediate the cyclization of β-amino acids with remarkable product yields. Compared to other cyclodehydrating agents, these have been found to be superior in terms of their cost, making them industrially viable. The advantageous properties of MBTS and LR make them useful and unique additions to the arsenal of cyclodehydrating agents.
Competitive endo- and exo-cyclic C-N fission in the hydrolysis of N-aroyl β-lactams
Tsang, Wing Y.,Ahmed, Naveed,Hemming, Karl,Page, Michael I.
, p. 1432 - 1439 (2007/10/03)
The balance between endo- and exo-cyclic C-N fission in the hydrolysis of N-aroyl β-lactams shows that the difference in reactivity between strained β-lactams and their acyclic analogues is minimal. Attack of hydroxide ion occurs preferentially at the exocyclic acyl centre rather than that of the β-lactam during the hydrolysis of N-p-nitrobenzoyl β-lactam. In general, both endo- and exo-cyclic C-N bond fission occurs in the alkaline hydrolysis of N-aroyl β-lactams, the ratio of which varies with the aryl substituent. Hence, the Bronsted β-values differ for the two processes: -0.55 for the ring-opening reaction and -1.54 for the exocyclic C-N bond fission reaction. For the pH-independent and acid-catalysed hydrolysis of N-benzoyl β-lactam, less than 3% of products are derived from exocyclic C-N bond fission.
(Chloromethylene)dimethylammonium chloride: A highly efficient reagent for the synthesis of β-lactams from β-amino acids
Kanwar, Seema,Sharma, Sain D.
, p. 705 - 707 (2007/10/03)
(Chloromethylene)dimethylammonium chloride 1, is a unique reagent that conveniently and efficiently mediates the amide bond formation in β-lactams via cyclodehydration of β-amino acids leading to β-lactam formation. The process involves the formation of a highly reactive activated ester of a β-amino acid which gets cyclised to the corresponding β-lactam in excellent yield. The reaction proceeds smoothly and cleanly as the by-products formed are the water soluble-dimethyl formamide and triethylamine hydrochloride.
Kinetics and Mechanism of Hydrolysis of N-Acyloxymethyl Derivatives of Azetidin-2-one
Valente, Emilia,Gomes, Jose R. B.,Moreira, Rui,Iley, Jim
, p. 3359 - 3367 (2007/10/03)
The pH-independent, acid-catalyzed and base-catalyzed hydrolyses of N-acyloxymethylazetidin-2-ones all occur at the ester function. The pH-independent hydrolysis involves rate-limiting alkyl C-O fission and formation of an exocyclic β-lactam iminum ion. This iminium ion is then trapped by water at the exocyclic iminium carbon atom, rather than at the β-lactam carbonyl carbon atom, to form the corresponding N-hydroxymethylazetidin-2-ones. Calculations carried out at the B3LYP/6-31+G(d) level of theory also support that nucleophilic attack by water takes place at the exocyclic carbon rather than at the β-lactam carbonyl carbon of the iminium ion. The mechanism for the acid-catalyzed pathway involves a preequilibrium protonation, probably at the β-lactam nitrogen, followed by rate-limiting alkyl C-O fission with formation of an exocyclic iminum ion. The base-catalyzed hydrolysis involves rate-limiting hydroxide attack at the ester carbonyl carbon. These results imply formation of a β-lactam system containing a positively charged amide nitrogen atom that hydrolyzes via a pathway that preserves the β-lactam structure in the product and provide further evidence that cleavage of the β-lactam C-N bond is not as facile as is commonly imagined.
Intermediates for and synthesis of 3-methylene cephams
-
, (2008/06/13)
The present invention relates to novel processes for the preparation of 3-methylenecephams. More specifically, the present invention relates in part to the intramolecular cyclization of penicillin sulfoxide derived monocyclic azetidinone derivatives either thermally or with lanthanide metal salt catalysts.
A simple synthetic protocol for the protection of amides, lactams, ureas, and carbamates
Reddy, Dandu R,Iqbal, Mohamed A,Hudkins, Robert L,Messina-McLaughlin, Patricia A,Mallamo, John P
, p. 8063 - 8066 (2007/10/03)
A new procedure for protecting the amide, lactam, urea, and carbamate NH group with a triphenylmethyl (Tr) group is described. The utility of this method is illustrated with molecules that contain other functional groups. A mild deprotection using trifluoroacetic acid makes this a useful method for attaching amide groups on resin for combinatorial synthesis.
