Phenolate-induced, diastereo- and regioselective intramolecular exo-tet ring-opening cyclization of N-tosylaziridines has been achieved for the first time. The N-tosylaziridine substrates bearing a tethered (ortho-(tert-butyldimethylsiloxy))aryl substituent, prepared directly from the corresponding olefins under Sharpless aziridination conditions, furnished functionalized 2,3-dihydrobenzofuran, chroman, and 1-benzoxepane derivatives in excellent yields when treated with tetrabutylammonium fluoride (TBAF) at room temperature. Our ability to synthesize benzoxacycle-based N-tosyl-protected amino alcohols, that are otherwise difficult to obtain by traditional synthetic routes, has opened the door to diversify the chemistry of β-amino alcohols. We also succesfully performed the Baeyer-Villiger oxidation of a salicylaldehyde ether bearing a tethered N-tosylaziridine moiety with m-CPBA followed by tandem saponification and 6-exo-tet aziridine ring-opening cyclization, furnishing the corresponding trans-3,4-disubstituted-1,4-benzodioxane derivative. Overall, the study has unveiled a new entry to the synthesis of benzoxacycles and has also broadened the impact of aziridines as synthetic building blocks.
A regio- and diastereoselective synthesis of pharmaceutically relevant 1,4-benzoxazine-fused benzothiaoxazepine-1,1-dioxides has been achieved under transition metal-free mild reaction conditions.
Herein, we report that the trifluoroethanol-mediated intramolecular ring opening cyclization of 4-(oxiran-2-ylmethoxy)indoles takes place in diastereoselective and 6-endo fashion to generate pyrano[2,3-e]indol-3-ols in high yields. This regioselective cyclization at indole...
The technology of electro-rheological fluids is old, but now it is being used in market at high speed. In the near future, ER fluids may be used for structure design where accuracy, density and power density are primarily the main criteria. For minimizing the costs and maximizing the functionality of the products, like where the viscosity of the fluid is varied to design, solid structure ER fluids are used. Features like fast response and easy interface between electrical and mechanical input–output makes the ER fluid attractive to various technology fields. In this study, ER fluids’ working principle, various low-cost ER fluids working procedures and ER fluid applications in multiple areas are explained.
Indole-3,4- and 4,5-fused carbo- and heterocycles are ubiquitous in bioactive natural products and pharmaceuticals, and hence, a variety of synthetic approaches toward such compounds have been developed. Among these, cyclization and annulation of 3,5-unsubstituted, 4-substituted indoles involving an electrophilic aromatic substitution (SEAr) as the ring closure are particularly attractive, because they avoid the use of 3,4- or 4,5-difunctionalized indoles as starting materials. However, since 3,5-unsubstituted, 4-substituted indoles have two potential ring-closure sites (indole C3 and C5 positions), such reactions in principle can furnish either or both of the indole 3,4- and 4,5-fused ring systems. This Commentary will briefly highlight the issue by summarizing recent relevant literature reports.
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