Palladium-Catalyzed Cyanothiolation of Internal Alkynes Using Organic Disulfides andtert-Butyl Isocyanide

Abstract

Despite the availability of selective synthetic approaches to multifunctionalized substituted olefins, the cyanothiolation of internal alkynes has been much less explored. Herein, we show that nonactivated internal alkynes can be successfully cyanothiolated with diaryl disulfides and tert-butyl isocyanide in the presence of a Pd catalyst (e.g., Pd(PPh)) with the release of isobutene and arenethiol to afford β-thiolated alkenyl cyanides in yields of 34-89%.

Dual Functionalization of Alkynes Utilizing the Redox Characteristics of Transition Metal Catalysts

“…[56] The same group also reported Pd(PPh 3 ) 4 catalyzed antiselective cyanothiolation across internal alkynes using tertbutylisocyanide 303 and organic disulfide 302 (Scheme 49). [57] An excess amount of alkyne and isocyanide dramatically increased the yield. With symmetrical alkyne, an E-selective product was observed.…”

Recent Advances in Palladium-Catalyzed Isocyanide Insertions

“…Additionally, selenocarbamate analogues of 160 displayed similar reactivity, affording the corresponding products in 41-64%. Another unconventional Liebeskind-Srogl-type activation proceeds via the oxidative addition of disulfide 164 to the active Pd 0 catalyst, followed by thiopalladation of the internal alkyne 163 (Scheme 46) [85]. The resulting vinylpalladium species 167 can undergo isocyanide insertion, after which δ-hydride elimination of the intermediate imidoyl palladium species 168 affords the β-thiolated acrylonitrile 164, isobutene, and a thiol, while regenerating the Pd 0 catalyst.…”

Cross-Dehydrogenative Coupling of Azoarenes with Dialkyl Disulfides

“…We herein report the direct construction of the C–N bond to afford unsymmetrical disulfides by the cross-dehydrogenative coupling (CDC) reaction of disulfides with purines and some azoarenes (Scheme c). Although a number of radical coupling reactions of disulfides have been reported, there is no precedent about the coupling reaction of α-C­(sp 3 )–H of disulfides, probably because the disulfide (S–S) bond was potentially too fragile to tolerate under harsh conditions.…”