Cross-Dehydrogenative Coupling Of Terminal Alkynes Research Articles

Cover Feature: Tuning the Selectivity of AuPd Nanoalloys towards Selective Dehydrogenative Alkyne Silylation (Chem. Eur. J. 23/2019)

It takes two to tandem! Tailor-made AuPd nanoalloys were developed for the selective cross-dehydrogenative coupling of terminal alkynes and hydrosilanes. Although monometallic Au nanoparticles do not catalyze that transformation, monometallic Pd nanoparticles show low selectivity for the desired alkynylsilane. The catalyst with cooperatively interacting Au and Pd metals tolerates a large number of functional groups and works at room temperature under air atmosphere. More information can be found in the Communication by M. Wissing and A. Studer on page 5870.

Tuning the Selectivity of AuPd Nanoalloys towards Selective Dehydrogenative Alkyne Silylation

The cross-dehydrogenative coupling of terminal alkynes and hydrosilanes catalyzed by AuPd nanoalloys is described. Metal nanoparticles are readily prepared in 15 minutes from commercially available and cheap starting materials by using a photochemical approach. The ratio of Au and Pd in the alloys heavily influences their reactivity. These cooperative nanoalloy catalysts tolerate a large number of functional groups (e.g., free amines and acids), operate at room temperature under air atmosphere at low loading (2 mol %), and the cross-dehydrogenative coupling can easily be scaled up.

Chemoselective Aerobic Cross-Dehydrogenative Coupling of Terminal Alkynes with Hydrosilanes by a Nanoporous Gold Catalyst.

Aerobic cross-dehydrogenative coupling between terminal alkynes and hydrosilanes occurred in the presence of nanoporous gold catalyst under O2 atmosphere. A variety of alkynylsilanes were synthesized in good-to-high yields and the catalyst was easily recovered and reused many times. Furthermore, the chemoselective direct silyl protection of terminal acetylenes of alkynols over the hydroxyl groups was achieved with this catalytic system.

A heterogeneous copper(I)-catalyzed aerobic oxidative cross-dehydrogenative coupling of terminal alkynes with thiols leading to alkynyl sulfides

A heterogeneous copper-catalyzed direct oxidative cross-dehydrogenative coupling of terminal alkynes with thiols was achieved in DMSO at 70°C in the presence of an MCM-41-supported bidentate nitrogen copper(I) complex [MCM-41-2N-CuCl] and K2CO3 under an atmosphere of O2, yielding selectively a variety of alkynyl sulfides in good to excellent yields. This heterogeneous copper catalyst can be easily recovered by a simple filtration and recycled 10 times without any decreases in activity.

Dehydrogenative and decarboxylative C–H alkynylation of heteroarenes catalyzed by Pd(II)–carbene complex

The direct alkynylation of heteroarenes was accomplished with easily prepared Pd(II) carbene complex (Pd Cat.) by two complementary strategies. Pd Cat. catalysed cross-dehydrogenative coupling of terminal alkynes with heteroarenes was achieved in the first method and decarboxylative coupling of aryl propiolic acids with heteroarenes was investigated in the second method. Both the methodologies tolerate a broad variety of heteroarenes that include benzoxazoles, benzothiazoles, imidazole and benzimidazoles.

Aerobic cross-dehydrogenative coupling of terminal alkynes and tertiary amines by a combined catalyst of Zn2+and OMS-2

In the presence of ZnBr2and OMS-2, cross-dehydrogenative coupling of various terminal alkynes and tertiary amines to propargylamines efficiently proceeded.

Cu(i)-catalyzed aerobic cross-dehydrogenative coupling of terminal alkynes with thiols for the construction of alkynyl sulfides

Highly active and selective aerobic cross-dehydrogenative coupling of terminal alkynes with thiols to construct alkynyl sulfides catalyzed by Cu(I) using molecular oxygen as the oxidant has been demonstrated under mild reaction conditions. The process is applicable to a wide range of alkynes and various thiols and is compatible with a variety of functional groups on both alkyne and thiol coupling partners.