Selective synthesis of pyridyl pyridones and oxydipyridines by transition-metal-free hydroxylation and arylation of 2-fluoropyridine derivatives.

An efficient protocol for the construction of various pyridyl pyridone and oxydipyridine derivatives through a hydroxylation and arylation tandem reaction of 2-fluoropyridines is reported. Under simple transition-metal-free conditions, the reaction provided a series of products in good to excellent yields, and their structures were confirmed by crystal diffraction analysis. Furthermore, the controlling effect of 6-position substituents on the highly selective synthesis of pyridone and oxydipyridine was studied.

NH4I-Promoted and H2O-Controlled Intermolecular Bis-sulfenylation and Hydroxysulfenylation of Alkenes via a Radical Process.

An NH4I-promoted and H2O-controlled intermolecular difunctionalization of alkenes for the synthesis of bis-methylsulfane and ß-hydroxysulfides is presented. Mechanistic investigation revealed the reaction proceeds via methylthiyl radical addition to C═C of alkenes to give a carbon-centered radical and immediately cyclize to a thiiranium ion, followed by combination with H2O to afford ß-hydroxysulfides in 52-89% yields with chemo- and regioselectivities. In the absence of water, 1,2-disulfenylation takes place to give bis-methylsulfane in moderate to good yields.

Ruthenium(ii)/acetate catalyzed intermolecular dehydrogenative ortho C-H silylation of 2-aryl N-containing heterocycles.

The first application of a RuHCl(CO)(PPh3)3-OAc catalytic system on the selective intermolecular mono C-H silylation of 2-aryl N-heterocycles using HSiEt3 as the silylating reagent has been described. This protocol features good functional group tolerance and high regioselectivity, and has potential for gram scale-up, which provides a convenient and practical pathway for the synthesis of versatile organosilane compounds. This catalytic system can also be applied to the silylation of challenging sp3 C-H bonds.

Electrochemical vicinal aminotrifluoromethylation of alkenes: high regioselective acquisition of ß-trifluoromethylamines.

A novel vicinal aminotrifluoromethylation of alkenes using CF3SO2Na as a trifluoromethyl precursor and acetonitrile as an N-nucleophile has been achieved by an electrooxidative strategy. The present electrochemical protocol achieves efficient and highly regioselective difunctionalization of C[double bond, length as m-dash]C bonds under metal-free and external oxidant-free electrolysis conditions, leading to a series of ß-trifluoromethylamine compounds with good to excellent yields. It is confirmed that the reaction involves free radical processes since CF3 radicals are trapped by scavengers and the ß-trifluoromethylated radical is trapped by BHT, and the deuterium-labeling experiments prove that the oxygen in the product comes from water.

(Z)-Tetrahydrothiophene and (Z)-tetrahydrothiopyran synthesis through nucleophilic substitution and intramolecular cycloaddition of alkynyl halides and EtOCS2K.

This protocol provides a novel, environmentally friendly and simple method for the synthesis of (Z)-tetrahydrothiophene derivatives using the nucleophilic thiyl radical intramolecular cycloaddition cascade process to construct C-S bonds under transition-metal-free conditions. This transformation process offers a broad substrate scope, good functional group tolerance, and excellent stereoselectivity (Z/E ratios up to 99/1). Moreover, the process uses odourless, stable and cheap EtOCS2K as the sulfur source.

Transition-metal-free access to 2-aminopyridine derivatives from 2-fluoropyridine and acetamidine hydrochloride.

Under catalyst-free conditions, an efficient method for the synthesis of 2-aminopyridine derivatives through the nucleophilic substitution and hydrolysis of 2-fluoropyridine and acetamidine hydrochloride has been developed. This amination uses inexpensive acetamidine hydrochloride as the ammonia source and has the advantages of a high yield, high chemoselectivity and wide substrate adaptability. The results suggest that other N-heterocycles containing fluorine substituents can also complete the reaction via these reaction conditions and yield the target products.