Herein a versatile HOTf-catalyzed and solvent-free system for highly efficient one-pot synthesis of privileged benzene and pyridine derivatives has been developed using ketones and ketones with amines as simple substrates, respectively. The remarkable features of this “green” reaction include good to excellent yields, exclusive chemoselectivity and broad substrate/functional group tolerance.

A new, efficient, and versatile Pd(II)-catalyzed oxidative three-component cascade reaction of diverse amines, alkyne esters, and alkenes is disclosed for the direct synthesis of diverse 2,3,4-trisubstituted pyrroles with broad functional group tolerance and in good to excellent yields. This transformation is supposed to proceed through the cascade formation of C(sp2)–C(sp2) and C(sp2)–N bonds via Pd(II)-catalyzed regioselective alkene migratory insertion, intramolecular radical addition, and oxidation sequential processes.

Ir(III)-catalyzed direct C–H alkynylation of arenes has been developed using commercially available TIPS-acetylene as an efficient alkynylating reagent, where O-NHAc was employed as an autocleavable oxidizing-directing group (ODGauto), thus giving rise to ortho-alkynylated phenols under mild reaction conditions in a highly efficient and redox-neutral manner. The reaction proceeded with high regioselectivity and broad substrate/functional group (FG) tolerance. The synthetic application of the products has been briefly exemplified. Preliminary mechanistic studies have been conducted, and a five-membered iridacycle has also been identified as a key intermediate.Keywords: C−H alkynylation; Ir(III); N-phenoxyacetamides; reaction mechanism; TIPS-acetylene

Herein we disclose the first example of Rh(III)-catalyzed intermolecular annulation of indoles with terminal alkynes to give highly efficient one-pot access to privileged carbazoles. The mild reaction features moderate to good yields, exclusive regioselectivity, broad substrate scope, and excellent functional group tolerance.

Here a new, mild and versatile method for one-pot cascade synthesis of diverse N-methoxyisoquinolinediones via Rh(III)-catalyzed regioselective carbenoid insertion C–H activation/cyclization of N-methoxybenzamides with α-diazotized Meldrum’s acid has been achieved. Extension of the developed Rh(III) catalysis for building new analogs of the marketed drug Edaravone has also been demonstrated.

Here we report a new and mild Rh(III)-catalyzed and alcohol-involved carbenoid C–H insertion into N-phenoxyacetamides using α-diazomalonates. This reaction provided a straightforward way for installing both an α-quaternary carbon center and a free-OH moiety into the phenyl ring, thus giving access to useful 2-(2-hydroxyphenyl)-2-alkoxymalonates with good substrate/functional group tolerance.

•Parent compounds were found to be the potent tyrosinase activators.•Structure-based modification toward parent compounds resulted in a remarkable change of the potency on tyrosinase.•All the designed compounds exhibited remarkable tyrosinase inhibitory activities.•SARs were discussed.•The inhibition mechanism and the inhibition kinetics of selected compounds on tyrosinase were investigated.In this study, we developed 3-/4-aminoacetophenones and their structure-based 3-/4-aminophenylethylidenethiosemicarbazide derivatives, respectively, as novel tyrosinase activators and inhibitors. Notably, all the obtained thiosemicarbazones displayed more potent tyrosinase inhibitory activities than kojic acid. Especially, compound 7k was found to be the most active tyrosinase inhibitor with IC50 value of 0.291 μM. The structure-activity relationships (SARs) analysis showed that: (1) the amine group was absolutely necessarily for determining the tyrosinase activation activity; (2) the introduction of thiosemicarbazide group played a very vital role in transforming tyrosinase activators into tyrosinase inhibitors; (3) the phenylethylenethiosemicarbazide moiety was crucial for determining the tyrosinase inhibitory activity; (4) the type of acyl group had no obvious effect on the inhibitory activity; (5) the position of amide substituent on the phenyl ring influenced the tyrosinase inhibitory potency. Moreover, the inhibition mechanism and inhibition kinetics study revealed that compound 7k was reversible and non-competitive inhibitor, and compound 8h was reversible and competitive-uncompetitive mixed-II type inhibitor.

The evolution of glucocorticoid drugs was driven by the demand of lowering the unwanted side effects, while keeping the beneficial anti-inflammatory effects. Potency is an important aspect of this evolution as many undesirable side effects are associated with use of high-dose glucocorticoids. The side effects can be minimized by highly potent glucocorticoids that achieve the same treatment effects at lower doses. This demand propelled the continuous development of synthetic glucocorticoids with increased potencies, but the structural basis of their potencies is poorly understood. To determine the mechanisms underlying potency, we solved the X-ray structures of the glucocorticoid receptor (GR) ligand-binding domain (LBD) bound to its endogenous ligand, cortisol, which has relatively low potency, and a highly potent synthetic glucocorticoid, mometasone furoate (MF). The cortisol-bound GR LBD revealed that the flexibility of the C1-C2 single bond in the steroid A ring is primarily responsible for the low affinity of cortisol to GR. In contrast, we demonstrate that the very high potency of MF is achieved by its C-17α furoate group completely filling the ligand-binding pocket, thus providing additional anchor contacts for high-affinity binding. A single amino acid in the ligand-binding pocket, Q642, plays a discriminating role in ligand potency between MF and cortisol. Structure-based design led to synthesis of several novel glucocorticoids with much improved potency and efficacy. Together, these results reveal key structural mechanisms of glucocorticoid potency and provide a rational basis for developing novel highly potent glucocorticoids.

Here a new, mild and versatile method for efficient synthesis of a diverse range of 2-acetate substituted indoles via Rh(III)-catalyzed and alcohol-mediated C2-selective carbenoid insertion functionalization of indoles by α-diazotized Meldrum's acid has been developed. Furthermore, for the first time, a Rh(III)/Cu(II)-catalyzed direct C7-alkenylation of such functionalized products has also been demonstrated.

A new and efficient method for the direct regioselective C2-amidation of various functionalized indoles with several N-(2,4,6-trichlorobenzoyloxy)amides via Rh(III)-catalyzed C–H activation/N–O cleavage/C–N formation using the pyrimidyl group as a readily installable and removable directing group has been developed. With this method, a variety of valuable 2-amido indoles can be easily prepared under mild conditions with broad functional group tolerance and excellent region-/site-specificities. Application of this strategy to the synthesis of target compound 6 as a novel PPARγ modulator was also demonstrated. The results from biological evaluation showed that compound 6 had a partial PPARγ agonistic activity and a strong PPARγ binding affinity with an IC50 value of 120.0 nM, along with a less pronounced adipocyte differentiation ability compared to the currently marketed anti-diabetic drug rosiglitazone, suggesting that further development of such a compound might be of great interest.

Green chemistry that uses water as a solvent has recently received great attention in organic synthesis. Here we report an efficient synthesis of biologically important isocoumarins through direct cleavage of C–H/O–H bonds by microwave-accelerated and Rh/Cu-catalyzed oxidative annulation of various substituted benzoic acids, where water is used as the only solvent in the reactions. The remarkable features of this “green” methodology include high product yields, wide tolerance of various functional groups as substrates, and excellent region-/site-specificities, thus rendering this methodology a highly versatile and eco-friendly alternative to the existing methods for synthesizing isocoumarins and other biologically important derivatives such as isoquinolones.

Here a new, mild and versatile method for one-pot cascade synthesis of diverse N-methoxyisoquinolinediones via Rh(III)-catalyzed regioselective carbenoid insertion C–H activation/cyclization of N-methoxybenzamides with α-diazotized Meldrum’s acid has been achieved. Extension of the developed Rh(III) catalysis for building new analogs of the marketed drug Edaravone has also been demonstrated.

A new and efficient method for the direct regioselective C2-amidation of various functionalized indoles with several N-(2,4,6-trichlorobenzoyloxy)amides via Rh(III)-catalyzed C–H activation/N–O cleavage/C–N formation using the pyrimidyl group as a readily installable and removable directing group has been developed. With this method, a variety of valuable 2-amido indoles can be easily prepared under mild conditions with broad functional group tolerance and excellent region-/site-specificities. Application of this strategy to the synthesis of target compound 6 as a novel PPARγ modulator was also demonstrated. The results from biological evaluation showed that compound 6 had a partial PPARγ agonistic activity and a strong PPARγ binding affinity with an IC50 value of 120.0 nM, along with a less pronounced adipocyte differentiation ability compared to the currently marketed anti-diabetic drug rosiglitazone, suggesting that further development of such a compound might be of great interest.

Here a new, mild and versatile method for efficient synthesis of a diverse range of 2-acetate substituted indoles via Rh(III)-catalyzed and alcohol-mediated C2-selective carbenoid insertion functionalization of indoles by α-diazotized Meldrum's acid has been developed. Furthermore, for the first time, a Rh(III)/Cu(II)-catalyzed direct C7-alkenylation of such functionalized products has also been demonstrated.

Here we report a new and mild Rh(III)-catalyzed and alcohol-involved carbenoid C–H insertion into N-phenoxyacetamides using α-diazomalonates. This reaction provided a straightforward way for installing both an α-quaternary carbon center and a free-OH moiety into the phenyl ring, thus giving access to useful 2-(2-hydroxyphenyl)-2-alkoxymalonates with good substrate/functional group tolerance.

Herein we disclose the first example of Rh(III)-catalyzed intermolecular annulation of indoles with terminal alkynes to give highly efficient one-pot access to privileged carbazoles. The mild reaction features moderate to good yields, exclusive regioselectivity, broad substrate scope, and excellent functional group tolerance.