Beta-ketophosphonates as beta-lactamase inhibitors: Intramolecular cooperativity between the hydrophobic subsites of a class D beta-lactamase

A Ni-catalyzed asymmetric C(sp)-P cross-coupling reaction for the synthesis of P-stereogenic alkynylphosphines

Due to the high reactivity of the triple bond, P-stereogenic alkynylphosphines could be easily derivatized, serving as universal building blocks for structurally diverse phosphine compounds. However, the synthesis of alkynylphosphines via direct P-C bond formation was unprecedented. Here, we report an efficient method for the synthesis of P-stereogenic alkynylphosphines with high enantioselectivity via a Ni-catalyzed asymmetric cross-coupling reaction. The reaction could tolerate a variety of functional groups, affording products that can be converted into useful phosphine derivatives.

Hydrophosphorylation of Electron-Deficient Alkenes and Alkynes Mediated by Convergent Paired Electrolysis

A straightforward and practical strategy for hydrophosphorylation of electron-deficient alkenes and alkynes to access γ-ketophosphine oxides, enabled by a convergent paired electrolysis (CPE) in the absence of metal, base, and...

Recent trends in the direct oxyphosphorylation of C-C multiple bonds

Due to the wide importance of β-phosphorylated ketones as key building-blocks in the fabrication of various pharmaceutically active organophosphorus compounds, finding new and truly efficient methods for their preparation from simple, low-cost and ubiquitous feedstock materials within a single click is an interesting subject in organic synthesis. Recently, oxyfunctionalization of carbon-carbon multiple bonds has arisen as a straightforward and versatile tool for the synthesis of complex organic molecules from the simple and easily accessible alkenes/alkynes via a single operation. In this context, oxyphosphorylation of alkenes/alkynes with P(O)-H compounds has attracted considerable attention as a unique procedure for the construction of β-phosphorylated ketones. In this review, we outline the recent advances and developments in this fast-growing research field with particular emphasis on the mechanistic aspects of reaction.

Copper-Catalyzed Direct Twofold C-P Cross-Coupling of Unprotected Propargylic 1,4-Diols: Access to 2,3-Bis(diarylphosphynyl)-1,3-butadienes

The first facile and efficient Cu-catalyzed direct coupling of unprotected propargylic diols with H-phosphine oxides was developed, providing a practical approach to access structurally diverse 2,3-bis(diarylphosphynyl)-1,3-butadienes along with the formation of two new P-C_sp² and two new C═C bonds under ligand- and base-free conditions.

Iron(iii)-catalyzed radical α,β-aminophosphinoylation of styrenes with diphenylphosphine oxides and anilines

A Fe-catalyzed highly regioselective α,β-difunctionalization of vinylarenes with diphenylphosphine oxides and anilines is disclosed, in which α,β-aminophosphinoylation is efficiently and conveniently constructed with good functional compatibility and a broad substrate scope.

Cu(i)/Fe(iii)-Catalyzed C–P cross-coupling of styrenes with H-phosphine oxides: a facile and selective synthesis of alkenylphosphine oxides and β-ketophosphonates

Cu(i)/Fe(iii)-Catalyzed phosphorylation and oxyphosphorylation of styrenes with H-phosphonates which can be controlled by varying the reaction temperature are developed.

Direct synthesis of β-ketophosphonates and vinyl phosphonates from alkenes or alkynes catalyzed by CuNPs/ZnO

Ligand- and base-free direct synthesis of β-keto- and vinyl phosphonates catalysed by CuNPs/ZnO under air. Selectivity dependent on alkyne nature.

β-Ketophosphonates formation via deesterification or deamidation of cinnamyl/alkynyl carboxylates or amides with H-phosphonates

We report here an unprecedented Fe/Cu synergistically catalyzed deesterificative or deamidative oxyphosphorylation of unsaturated carboxylates or amides with H-phosphonates.

A one-pot strategy to synthesize β-ketophosphonates: silver/copper catalyzed direct oxyphosphorylation of alkynes with H-phosphonates and oxygen in the air

A highly efficient one-pot strategy has been developed for the synthesis of β-ketophosphonates directly from alkynes and dialkylH-phosphonates in the presence of widely available AgNO₃/CuSO₄and K₂S₂O₈at room temperature.

Current challenges in antimicrobial chemotherapy: focus on ß-lactamase inhibition

The use of the three classical beta-lactamase inhibitors (clavulanic acid, tazobactam and sulbactam) in combination with beta-lactam antibacterials is currently the most successful strategy to combat beta-lactamase-mediated resistance. However, these inhibitors are efficient in inactivating only class A beta-lactamases and the efficiency of the inhibitor/antibacterial combination can be compromised by several mechanisms, such as the production of naturally resistant class B or class D enzymes, the hyperproduction of AmpC or even the production of evolved inhibitor-resistant class A enzymes. Thus, there is an urgent need for the development of novel inhibitors. For serine active enzymes (classes A, C and D), derivatives of the beta-lactam ring such as 6-beta-halogenopenicillanates, beta-lactam sulfones, penems and oxapenems, monobactams or trinems seem to be potential starting points to design efficient molecules (such as AM-112 and LK-157). Moreover, a promising non-beta-lactam molecule, NXL-104, is now under clinical development. In contrast, an ideal inhibitor of metallo-beta-lactamases (class B) remains to be found, despite the huge number of potential molecules already described (biphenyl tetrazoles, cysteinyl peptides, mercaptocarboxylates, succinic acid derivatives, etc.). The search for such an inhibitor is complicated by the absence of a covalent intermediate in their catalytic mechanisms and the fact that beta-lactam derivatives often behave as substrates rather than as inhibitors. Currently, the most promising broad-spectrum inhibitors of class B enzymes are molecules presenting chelating groups (thiols, carboxylates, etc.) combined with an aromatic group. This review describes all the types of molecules already tested as potential beta-lactamase inhibitors and thus constitutes an update of the current status in beta-lactamase inhibitor discovery.

Intramolecular cooperativity in the reaction of diacyl phosphates with serine beta-lactamases

Asymmetric diaroyl phosphates (ArCOOPO(2)(-)OCOAr', where Ar = Ph, Ar' = 4-biphenyl, 2-benzothiophenyl and 2-benzofuranyl) have been prepared, evaluated as serine (classes A, C, and D) beta-lactamase inhibitors, and compared with respect to the latter with their symmetric parents, where Ar = Ar'. The asymmetric compounds, in general, were found to react with the beta-lactamases in two modes, corresponding to different orientations with respect to the active site, whereby either of the two aroyl groups may acylate the enzyme to form two different inert acyl-enzymes, E-COAr and E-COAr' . In all cases, the asymmetric compounds, in one orientation, react more rapidly with the enzymes tested than one symmetrical parent but not both. From comparisons of activation free energy differences, it was found that the changes in free energy on changing from one aryl group to another, in either the acyl group or the leaving group, were not additive, i.e., that the effect of changing one aroyl group to another depended on the leaving group and vice versa. Thus, intramolecular cooperativity between the aroyl groups must exist, arising either from direct interaction between them or from protein-mediated interaction or from a combination of both. Such cooperativity brings fresh opportunities and challenges to the search for novel beta-lactamase inhibitors.

Approaches to the simultaneous inactivation of metallo- and serine-beta-lactamases

A series of cephalosporin-derived reverse hydroxamates and oximes were prepared and evaluated as inhibitors of representative metallo- and serine-beta-lactamases. The reverse hydroxamates showed submicromolar inhibition of the GIM-1 metallo-beta-lactamase. With respect to interactions with the classes A, C, and D serine beta-lactamases, as judged by their correspondingly low K(m) values, the reverse hydroxamates were recognized in a manner similar to the non-hydroxylated N-H amide side chains of the natural substrates of these enzymes. This indicates that, with respect to recognition in the active site of the serine beta-lactamases, the OC-NR-OH functionality can function as a structural isostere of the OC-NR-H group, with the N-O-H group presumably replacing the amide N-H group as a hydrogen bond donor to the appropriate backbone carbonyl oxygen of the protein. The reverse hydroxamates, however, displayed k(cat) values up to three orders of magnitude lower than the natural substrates, thus indicating substantial slowing of the hydrolytic action of these serine beta-lactamases. Although the degree of inactivation is not yet enough to be clinically useful, these initial results are promising. The substitution of the amide N-H bond by N-OH may represent a useful strategy for the inhibition of other serine hydrolases.