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Chemical Synthesis of β-Lactams: Asymmetric Catalysis …

β-Lactam synthesis

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Elaboration of the lactam cores via amidation enabled synthesis of ..

An efficient, cost-effective and large-scale synthesis of ezetimibe 1, an antihypercholesterolemia drug, is described. Chiral oxazolidinone chemistry was used to fix the required stereochemistry of the β-lactam ring, and the chiral oxazaborolidine chemistry was used to fix the hydroxyl group stereochemistry. The synthesis significantly lowers the cost and provides easy access to ezetimibe on large scale.

AMA Citation Beta-Lactam Antibiotics & Other Cell Wall Synthesis Inhibitors

The development of a scalable asymmetric route to a new calcitonin gene-related peptide (CGRP) receptor antagonist is described. The synthesis of the two key fragments was redefined, and the intermediates were accessed through novel chemistry. Chiral lactam 2 was prepared by an enzyme mediated dynamic kinetic transamination which simultaneously set two stereocenters. Enzyme evolution resulted in an optimized transaminase providing the desired configuration in >60:1 /. The final chiral center was set via a crystallization induced diastereomeric transformation. The asymmetric spirocyclization to form the second fragment, chiral spiro acid intermediate 3, was catalyzed by a novel doubly quaternized phase transfer catalyst and provided optically pure material on isolation. With the two fragments in hand, development of their final union by amide bond formation and subsequent direct isolation is described. The described chemistry has been used to deliver over 100 kg of our desired target, ubrogepant.

Patent US7541458 - β-lactam synthesis - Google Patents

The described synthetic strategy provides pyrazolo-fused spirolactams from halogenated benzylic arenes and cyclic carboxylates.

The -lactam forms the center structure of many antibiotic drugs, such as the and the , as shown above. In the penicillins, the non-lactam ring is one atom smaller compared to the cephalosporins. The activity of cephalosporins, penicillins, and some other antibiotics are due to the presence of the beta-lactam, which binds irreversibly, via acylation, to penicillin-binding proteins, thereby inhibiting the peptidogycan layer of bacterial cell wall synthesis. Cephalosporins and penicillins are often made semi-synthetically, using a core structure obtained from a natural organism, such as a fungus, due to the difficulty and expense of synthesizing these lactams.

The four-membered ring appears to be the smallest cyclic system that is capable of accommodating the amide function as a constituent. Such four-membered cyclic amides are commonly referred to as beta-lactams. The reluctance with which beta-lactams are formed using conventional methods of lactam synthesis has necessitated unique approaches to the problem. After 1943, interest in beta-lactams was stimulated by the importance of natural penicillins. Although there are at present several useful approaches to the beta-lactam ring systems, the synthesis of beta-lactams by a single general method is not possible. In principle, the synthesis of the beta-lactam ring might be accomplished by the formation of one, two, three, or all four bonds of the ring during the cyclization step. Of these four possibilities, only the last has been realized.

Synthesis of β-Lactam Antibiotics ebook by - Rakuten Kobo

The hitherto unknown N-2 -butyl pyrazolospirolactam core was synthesized from ethyl 3-amino-1-pyrazole-4-carboxylate in a streamlined 10-step synthesis requiring only one chromatography procedure.

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    Synthesis of β-Lactam Antibiotics ebook by - Rakuten …

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