No abstract

A metal-free cross-dehydrogenative coupling method for the synthesis of N-substituted azoles has been developed. The TBAI/TBHP system catalyzed the coupling of azoles with ethers and thioethers via α-C(sp(3))-H activation. Under the optimized conditions, a diverse range of un/substituted azoles such as 1H-benzimidazole, 9H-purine, 1H-benzotriazole, 1H-1,2,3-triazole, 1H-1,2,4-triazole, and 1H-pyrazole were successfully employed for coupling with various ethers and thioethers such as tetrahydrofuran, tetrahydropyran, 1,4-dioxane, diethyl ether, tetrahydrothiophene, and 1,3-dithiolane.

We report a new and efficient iron oxide catalyzed cross-coupling reaction between organometallic species such as alkyl/arylmagnesium halides or organolithium species and α-hydrogen bearing cyclic aliphatic ethers via activation of C(sp(3))-H. This is the first example of iron oxide mediated direct C-C bond formation without expensive or toxic ligands.

An unprecedented enantioselective oxa-Michael reaction of α-tertiary alcohols using cinchona-alkaloid-based chiral bifunctional squaramide catalysts is reported. An oxidative dearomatization of phenol followed by an enantioselective oxa-Michael addition sequence provided a broad array of chiral sterically hindered tetrahydrofurans and tetrahydropyrans attached to a cyclohexadienone moiety in spiro fashion. In general, good yields and excellent enantioselectivities (up to 99 %) were observed. The chiral oxo-cycles obtained have easily been transformed into chromans without disturbing the enantioselectivity.

We report a new and efficient iron oxide catalyzed cross-coupling reaction between organometallic species such as alkyl/arylmagnesium halides or organolithium species and α-hydrogen bearing cyclic unbranched and branched aliphatic ethers via activation of C(sp(3))-H. In the presence of 1 mol% of iron oxide, five and six membered unbranched cyclic ethers such as tetrahydrofuran and tetrahydropyran gave good to excellent yields of cross-coupled products. Whereas, in case of branched ether such as 2-methyltetrahydrofuran, it was observed that the arylation occurred at both the sides and gave moderate yields of a mixture of regioisomers. Among the organometallic species used, alkyl organometallic reagents gave less yields as compared to aryl organometallics.

Ultraviolet radiation (UVR) is the major exogenous agent that disturbs tissue homeostasis and hastens the onset of age‐related phenotypes (photoaging). Exposure to UV‐B radiation promotes apoptosis in human skin cells via induction of Reactive Oxygen Species (ROS)‐mediated Endoplasmic Reticulum (ER) stress by activating the PERK‐eIF2α‐CHOP pathway, which plays a major role in exacerbating skin photoaging. Alleviating the production of ROS and boosting the antioxidant capacity of cells is the foremost therapeutic strategy to avert the repercussions of ultraviolet radiation exposure. In this study, we investigated the role of 3‐(1′‐methyltetrahydropyridinyl)‐2,4‐6‐trihydroxy acetophenone (IIIM‐8) in thwarting the UV‐B‐induced photoaging. We observed that IIIM‐8 ameliorates UV‐B‐induced oxidative stress, ER stress, Loss of Mitochondrial membrane potential, MAPK activation and Inflammation in irradiated skin cells. Ultraviolet radiation‐related damage to fibroblasts within the dermis leads to collagen degradation‐the hallmark of photoaging. IIIM‐8 substantially restored the synthesis of collagen and prevented its degradation via the downregulation of matrix metalloproteinases. Topical application of IIIM‐8 prevented BALB/c mice skin from UV‐B‐induced leukocyte infiltration, epidermal thickening and disruption of Extracellular matrix components. Implying that IIIM‐8 has a strong photoprotective property and has potential to be developed as a topical therapeutic/cosmeceutical agent against UV‐B‐induced photoaging.

The title method is performed with THF, tetrahydropyran, and 2‐methyltetrahydrofuran, and freshly prepared aryl/alkylmagnesium halides or organolithium compounds.

Iron Oxide Mediated Direct C-H Arylation/Alkylation at α-Position of Cyclic Aliphatic Ethers. -(SINGH, P. P.; GUDUP, S.; AMBALA, S.; SINGH, U.; DADHWAL, S.; SINGH, B.; SAWANT, S. D.; VISHWAKARMA*, R. A.; Chem. Commun. (Cambridge) 47 (2011) 20, 5852-5854, http://dx.doi.org/10.1039/c1cc11094b ; Med. Chem. Div., Indian Inst. Integr. Med., Jammu Tawi 180 001, India; Eng.) -R. Staver 38-105