Copper‐Catalyzed Synthesis of α‐Thioaryl Carbonyl Compounds Through SS and CC Bond Cleavage

Abstract

A method to access α‐thioaryl ketones and α‐thioaryl esters employing copper acetate (hydrate) as catalyst and readily accessible diaryl disulfides and β‐diketones (or β‐keto esters) has been developed. Both alkyl‐ and aryl‐substituted carbonyl compounds can be prepared.magnified image

Silver‐Catalyzed Oxidative C(sp3)−P Bond Formation through C−C and P−H Bond Cleavage

“…Importantly, this transformation was also amenable to β‐ketoamides (R 3 =NMe 2 or NEt 2 ) and β‐ketoesters (R 3 =OEt or OBn), in which C−C bond cleavage occurred exclusively at the amide or ester side of the substrate to afford the desired product 3 aa in good yield. These reactions proceeded in a different manner to those previously reported,, in which C−C bond cleavage usually occurred at the ketone side. For unsymmetrical diketones, C−C bond cleavage proceeded selectively at the less sterically hindered methyl ketone side to give 3 af – ai and 3 ak – aaa .…”

“…4]. On the basis of these observations and previous reports,, we envisioned that the reaction of 1 a with 2 a probably proceeded by oxidative C(sp 3 )−H/P−H cross‐coupling and a tandem C(sp 3 )−C(CO) bond‐cleavage reaction to provide the desired product 3 aa . To prove our hypothesis, we monitored changes in the levels of the different components of the reaction mixture over time (Figure ).…”

“…More recently, Jiao and co‐workers discovered a copper‐catalyzed oxidative esterification reaction, which involved sequential C−C bond‐breaking and C−O bond‐reconstruction reactions (Scheme b) . Almost simultaneously, Bolm and co‐workers reported a copper‐catalyzed C−S bond‐forming reaction, which proceeded through C−C and S−S σ‐bond cleavage involving 1,3‐dicarbonyl and disulfide substrates (Scheme c) . These pioneering reports have demonstrated that the formation of C−X bonds by the transition‐metal‐catalyzed selective cleavage of the C−C bond of a 1,3‐dicarbonyl compound is a powerful method for the target‐oriented synthesis of organic molecules.…”

Substituted α‐Sulfur Methyl Carbanions: Effective Homologating Agents for the Chemoselective Preparation of β‐Oxo Thioethers from Weinreb Amides

“…Similar electrophilic sulfur agents (e.g. disulfides) can be conveniently employed in the Bolm's Cu‐mediated sulfenylation of β‐oxocarbonyls ( path c ) . Metal‐catalyzed S–H insertion into diazocarbonyls are not preferred options as a consequence of the somewhat limited selectivity and efficiency ( path d ) .…”

Sulfenylation of β-Diketones Using C–H Functionalization Strategy

“…Recently, Bolm and coworkers reported a deacylative thiolation of β-diketones, using copper catalysts, and described that the deacylation is due to an attack by an unknown nucleophile, probably the residual water, on the carbonyl carbon. 11 Thus, the sulfenylation of β-diketones, without any deacylation, remains a challenge and such a loss of one acyl group limits the further manipulation of the product along with the loss of a potential chiral center. In continuation of our work in the formation of the C−S bond utilizing benzazoles (benzoxazole-2-thione and benzothiazole-2-thione) as a thiol equivalent, we envisaged the coupling of the benzazole with the β-diketone using K 2 S 2 O 8 to obtain α-sulfenylated β-diketones.…”