Late‐Stage Photocatalytic Fluoroalkylation of Aromatic Crown Ethers in Aqueous Media

Modified crown ethers are fundamental building blocks in supramolecular chemistry, with applications in phase transfer catalysis, metal extraction, smart materials, and molecular machines. Here we report on a one-pot highly chemo- and regioselective photocatalytic fluoroalkylation protocol for the mono-functionalization of benzo substituted crown ethers. For this important class of macrocycles, the method described here represents one of the few late-stage functionalization procedures that is both high yielding and scalable. Because of its breadth of scope and substrate tolerance, the devised approach can be applied to a wide range of aromatic crown ethers (18 examples, up to 99 % yield), including those engaged in mechanically interlocked molecules

Converging Fate of the Oxidation and Reduction of 8-Thioguanosine

Thione-containing nucleobases have attracted the attention of the scientific community for their application in oncology, virology, and transplantology. The detailed understanding of the reactivity of the purine derivative 8-thioguanosine (8-TG) with reactive oxygen species (ROS) and free radicals is crucial for its biological relevance. An extensive investigation on the fate of 8-TG under both reductive and oxidative conditions is here reported, and it was tested by employing steady-state photooxidation, laser flash photolysis, as well as gamma-radiolysis in aqueous solutions. The characterization of the 8-TG T-1 excited state by laser flash photolysis and the photooxidation experiments confirmed that singlet oxygen is a crucial intermediate in the formation of the unexpected reduced product guanosine, without the formation of the usual oxygenated sulfinic or sulfonic acids. Furthermore, a thorough screening of different radiolytic conditions upon gamma-radiation afforded the reduced product. These results were rationalized by performing control experiments in the predominant presence of each reactive species formed by radiolysis of water, and the mechanistic pathway scenario was postulated on these bases

Frontal fibrosing alopecia: A multicenter review of 355 patients

Background: To our knowledge, there are no large multicenter studies concerning frontal fibrosing alopecia (FFA) that could give clues about its pathogenesis and best treatment. Objective: We sought to describe the epidemiology, comorbidities, clinical presentation, diagnostic findings, and therapeutic choices in a large series of patients with FFA. Methods: This retrospective multicenter study included patients given the diagnosis of FFA. Clinical severity was classified based on the recession of the frontotemporal hairline. Results: In all, 355 patients (343 women [49 premenopausal] and 12 men) with a mean age of 61 years (range 23-86) were included. Early menopause was detected in 49 patients (14%), whereas 46 (13%) had undergone hysterectomy. Severe FFA was observed in 131 patients (37%). Independent factors associated with severe FFA after multivariate analysis were: eyelash loss, facial papules, and body hair involvement. Eyebrow loss as the initial clinical presentation was associated with mild forms. Antiandrogens such as finasteride and dutasteride were used in 111 patients (31%), with improvement in 52 (47%) and stabilization in 59 (53%). Limitations: The retrospective design is a limitation. Conclusions: Eyelash loss, facial papules, and body hair involvement were associated with severe FFA. Antiandrogens were the most useful treatment. ( J Am Acad Dermatol 2014;70:670-8.