Sulfenylation of β-Diketones Using C–HFunctionalization Strategy

Abstract

Sulfenylation of β-diketones is challenging as β-diketones undergo deacylation after sulfenylation in the reaction medium. The sulfenylation of β-diketones without deacylation under metal-free conditions at ambient temperature via a cross dehydrogenative coupling (CDC) strategy is reported. The resultant products can be further manipulated to form α,α-disubstituted β-diketones and pyrazoles.

A convenient and practical synthesis of β-diketones bearing linear perfluorinated alkyl groups and a 2-thienyl moiety

“…Commercial NaH is supplied in a relatively safe form of 60% dispersion in mineral oil. Although other researchers recommended to use this dispersion in native form [18–19 25], we have found that mineral oil should be removed before the synthesis. The results of the optimization experiments are summarized in Table 1.…”

“…It was found that mixing 2-acetylthiophene with a base in the absence of the ester (var. A) should be avoided due to notable darkening and self-condensation of the ketone, despite Prabhu’s recommendations [25]. Similar yields of a β-diketone were obtained if the ester of perfluorocarboxylic acid was first added to a base (var.…”

“…The best results were obtained if THF solution of carbonyl compounds was slowly added dropwise to a suspension of NaH in THF, while the temperature was maintained below +5 °C. Upon completion of the condensation, the reaction mixture should be kept at room temperature for 5–10 h, because prolonged reflux, as recommended by other researchers [19,25], notably decreases the yields and purity of β-diketones.…”

Iron‐Catalyzed Cross‐Dehydrogenative Coupling of Oxindoles with Thiols/Selenols for Direct C(sp3)−S/Se Bond Formation

“…[11] We commenced our studies by examining the reaction between indolin-2-one (1 a) and 4-chlorobenzenethiol (2 a) in the presence of a catalytic amount of iron salts (10 mol%) [3][4][5][6][7][8]. It was found that all the tested iron salts could drive the reaction, and FeCl 3 was shown the best efficiency to afford the [9][10][11][12]. The loading of the base was also optimized (entries 13 and 14).…”

“…The cross-dehydrogenative coupling (CDC) is one of the most straightforward and efficient approache in organic synthesis due to its high atom and step economy, avoiding prefunctionalization of starting materials. [8] However, the CDC methods for C(sp 3 )À X (S/Se) bonds construction are relatively less explored, [9] and many of them suffered limitations including typical substrates, strong oxidants and harsh reaction conditions. The development of a green and mild strategy leading to C(sp 3 )À X (S/Se) bonds formation is still a challenging task.…”