Palladium‐Catalyzed Tail‐to‐Tail Reductive Dimerization of Terminal Alkynes to 2,3‐Dibranched Butadienes

Abstract

The palladium‐catalyzed tail‐to‐tail reductive dimerization of terminal alkynes is described for the first time. Aromatic terminal alkynes bearing diverse and sensitive functional groups as well as aliphatic terminal alkynes are efficiently transformed to 2,3‐dibranched butadienes. The key to achieve a selective tail‐to‐tail reductive dimerization reaction is to control appropriately the acidity of the reaction solution, which is accomplished by a combined use of pivalic acid and para‐toluenesulfonic acid. The tail‐to‐tail reductive dimerization reaction is proposed to proceed via a cationic alkenyl palladium intermediate under acidic conditions.

Synthesis of Five-Membered Cyclic Phosphinic Acids via the [4C+1P] Cyclization of 1,3-Dienes with a Combination of PBr3 and P(OMe)3 as the P(III) Source

“…13 C­{ 1 H} NMR (126 MHz, chloroform- d ): δ 166.8, 148.6, 144.3, 129.6, 129.3, 127.4, 118.3, 52.1. The NMR data were consistent with those reported …”

“…The NMR data were consistent with those reported. 40 4,4′-(Buta-1,3-diene-2,3-diyl)bis((trifluoromethoxy)benzene) (1q). 4,4′-(Buta-1,3-diene-2,3-diyl)bis((trifluoromethoxy)benzene) (1q) was prepared from methyl 1-(4-(trifluoromethoxy)phenyl)ethan-1-one (2.0 g, 10.0 mmol).…”

Pd/Cu Cooperative Catalysis for Heteroarylation of Vinyl C–H Bond Forming Polyaryl Ethylenes via C–O/Dual C–H Cleavage

“…We can see that aryl bromides performed worse than the corresponding aryl triflates in all of the three cases. It is deduced that the higher yield of aryl triflates would be ascribed to their higher reactivity, while the more excellent regio -selectivity to vinyl C–H arylation would be attributed to the ionic nature of the resulting aryl palladium triflate generated via oxidative addition . It is reported that CsOPiv is essential to the previous aryl halide-based Pd shift/vinyl C–H activation strategy .…”

Metal-catalyzed Markovnikov-type selective hydrofunctionalization of terminal alkynes

“…In 2022, Bao and Li reported a palladium-catalyzed tail-to-tail reductive dimerization of terminal alkynes to synthesize 2,3-dibranched butadienes for the first time (Scheme 12(a)). 61 The formation of alkenyl palladium intermediate under acidic conditions plays an essential role in delivering diene products. The C–C coupling between alkene and alkyne is also explored to prepare conjugated diene.…”