DMSO–allyl bromide: a mild and efficient reagent for atom economic one-pot N-allylation and bromination of 2°-aryl amines, 2-aryl aminoamides, indoles and 7-aza indoles

A mixture of DMSO–allyl bromide–KOH has been developed as a reagent for one-pot N-allylation and aryl bromination of a number of 2°-aryl amines, aryl aminoamides, indoles, 7-aza indoles has been achieved.

Radical and Ionic Mechanisms in Rearrangements of o-Tolyl Aryl Ethers and Amines Initiated by the Grubbs–Stoltz Reagent, Et3SiH/KOtBu

Rearrangements of o-tolyl aryl ethers, amines, and sulfides with the Grubbs–Stoltz reagent (Et3SiH + KOtBu) were recently announced, in which the ethers were converted to o-hydroxydiarylmethanes, while the (o-tol)(Ar)NH amines were transformed into dihydroacridines. Radical mechanisms were proposed, based on prior evidence for triethylsilyl radicals in this reagent system. A detailed computational investigation of the rearrangements of the aryl tolyl ethers now instead supports an anionic Truce–Smiles rearrangement, where the initial benzyl anion can be formed by either of two pathways: (i) direct deprotonation of the tolyl methyl group under basic conditions or (ii) electron transfer to an initially formed benzyl radical. By contrast, the rearrangements of o-tolyl aryl amines depend on the nature of the amine. Secondary amines undergo deprotonation of the N-H followed by a radical rearrangement, to form dihydroacridines, while tertiary amines form both dihydroacridines and diarylmethanes through radical and/or anionic pathways. Overall, this study highlights the competition between the reactive intermediates formed by the Et3SiH/KOtBu system.

Base-Mediated Site-Selective Hydroamination of Alkenes

We present a base-mediated hydroamination protocol, using substoichiometric amounts of a hydrosilane and potassium tert-butoxide, that operates under mild conditions at 30 oC. Many aryl- and heteroatom-substituted olefins as well as aryl amines are tolerated, affording the desired products with complete regioselectivity. Preliminary mechanistic investigations reveal a non-radical pathway for hydroamination. A sequential remote hydroamination strategy involving an initial Fe-catalysed olefin isomerisation followed by our base-mediated hydroamination was also developed to directly access β-arylamines from terminal aliphatic alkenes.

New pyrido[3′,2′:4,5]thieno[3,2-d]pyrimidin-4(3H)-one hybrids linked to arene units: synthesis of potential MRSA, VRE, and COX-2 inhibitors

In the current study, we reported the tandem synthesis of two series of arene-linked pyrimidinone hybrids with related fused thieno[2,3-b]pyridine moiety. The target hybrids were prepared, in moderate to excellent yields, by the reaction of a ternary mixture of the appropriate of 3-aminothieno[2,3-b]pyridine-2-carboxylate, DMF-DMA, and a series of aryl amines in dioxane at 110 °C for 8 h. The antibacterial activity of the new hybrids was estimated against six susceptible ATCC strains. Hybrids 5g and 7g, linked to a sulfonamide unit, showed the best efficacy against S. aureus and E. faecalis strains with minimum inhibitory concentration (MIC) values of 1.7–1.8 μM, which exceed ciprofloxacin. Furthermore, some of new hybrids were examined as potential inhibitors of four different MRSA and VRE strains. Hybrids 5g and 7g demonstrated more potent efficacy than linezolid against MRSA strains with MIC values of 3.6/3.4 and 1.8/1.7 μM against ATCC:33591 and ATCC:43300 strains, respectively. The prior hybrids displayed a comparable efficacy with linezolid against VRE strains with MIC values of 7.3/6.9 and 3.6/3.4 μM against ATCC:51299 and ATCC:51575 strains, respectively. Additionally, some of the new hybrids were examined as potential COX-2 inhibitors using the reference celecoxib (IC50 of 0.117 µM). Hybrid 7g revealed more potent inhibitory efficacy than celecoxib with IC50 of 0.112 µM, whereas hybrid 5g showed almost inhibitory activity equivalent to celecoxib with IC50 of 0.121 µM. Molecular docking was performed to predict the possible binding interactions between hybrids 5g and 7g with the target COX-2 enzyme.

Synthesis of Benzenesulfonamide Derivatives Via Ring Opening of Aziridines In The Presence of Magnetically Retrievable Graphene Based (CoFe@rGO) Nanohybrid.

Graphene based magnetic nanohybrids have engrossed considerable research curiosity because of their exceptional properties and diverse applications associated with green chemistry. In this regard, a practical, facile and regioselective preparation of 1,2-diamines from N-tosylaziridine/(S)-(+)-2-Benzyl-1-(p-tolylsulfonyl)aziridine and aryl amines in the presence of magnetically separable graphene based nanohybrid (CoFe@rGO) has been proposed under mild and solvent free conditions. The FT-IR, FE-SEM, XRD and EDX spectroscopic analysis confirmed the formation of the CoFe@rGO nanohybrids. For unsymmetrical aziridine, nucleophilic attack of aryl amines was observed to take place selectively at the more substituted carbon atom of aziridine ring. Environmentally benign, efficient, shorter reaction time, solvent-free conditions, low catalyst loading, excellent reaction yields and reusability of the catalyst for six consecutive runs without significant loss in its activity are the key advantages of this protocol.