Highly Regioselective Thiocarbonylation of Conjugated Dienes via Palladium-Catalyzed Three-Component Coupling Reactions

Abstract

Three-component coupling reaction of conjugated dienes, thiols, and carbon monoxide affords an atom-economical thiocarbonylation of the dienes to give beta,gamma-unsaturated thioesters as the sole products. A catalyst system based on [Pd(OAc)(2)] and Ph(3)P showed excellent catalytic activity. The thiocarbonylation was performed under an atmosphere of carbon monoxide (400 psi) at 110 degrees C in CH(2)Cl(2) for 60 h. A wide variety of thioesters were synthesized in good to excellent yields from easily accessible starting materials. The reaction is believed to proceed via a eta(3)-allylpalladium intermediate. The thiocarbonylation, which is applicable to a wide variety of conjugated dienes, occurs in high regioselectivity, the latter dependent on the steric characteristics and stability of the eta(3)-allylpalladium complex.

Palladium‐Catalyzed 1,4‐Additions to Conjugated Dienes

“…11.2.1.6 1,4-Hydrosulfenation and 1,4-Hydrothiocarbonylation Palladium-catalyzed reaction of isoprene with thiophenol in the presence of CO gave, depending on the solvent, either a thiocarbonylation product (16a) or a product in which a 1,4-addition of sulfur and a hydrogen had occurred (16b) [31]. The reaction was optimized for the formation of the thiocarbonylation product (in CH 2 Cl 2 ) to give 1,4-addition products in good yields.…”

Transition-Metal-Catalyzed S–H and Se–H Bonds Addition to Unsaturated Molecules

“…The Pd(OAc) 2 /PPh 3 catalyst is very useful for the thiocarbonylation of a variety of carbon-carbon double-bond compounds such as conjugated dienes [118], allylic alcohols [119], and vinylcyclopropanes [120], as shown in Scheme 35. These reactions proceeds via p-allylpalladium complexes as key intermediates.…”

Reactions of Acylpalladium Derivatives with Oxygen, Nitrogen, and Other Group 15, 16, and 17 Atom Nucleophiles: Intermolecular Processes: Palladium-Catalyzed Hydrocarboxylation and Related Carbonylation Reactions ofπ-Bonded Compounds

“…[57 ]- [60] Recently, the carbonylation of dienes in the presence of thiophenol was achieved to give ␤,␥-unsaturated thioesters in fine yields. [62] The regioselectivity of the reaction depends mainly on steric factors of the dienes forming either the 1,2-or 1,4-products of addition with E-isomers predominant in all cases ( Table 1). In addition, the stereochemistry of the products is independent of the stereochemistry of the dienes (Eq.…”

“…For example, using dienes as reactants in the ratio of E/Z ϭ 1, E/Z ϭ 9.9, or Z/E ϭ 9.9, the major as well the as the minor ␤,␥-unsaturated thioesters have the E-stereoisomer as the dominant isomer. [62] The reaction probably proceeds via coordination of Pd-SPh to the less or the more substituted part of the double bond forming either CH 3 CH"C (PdSPh)CH 3 or PdSPhCH 2 CH"CCH 3 ; subsequent CO insertion followed by reductive elimination leads to the formation of the corresponding thioesters. [62] The direct thiocarbonylation of a series of mono-and disubstituted allenes with thiols and carbon monoxide also gave the corresponding ␤,␥-unsaturated thioesters in 73-94% yields.…”

“…[62] The reaction probably proceeds via coordination of Pd-SPh to the less or the more substituted part of the double bond forming either CH 3 CH"C (PdSPh)CH 3 or PdSPhCH 2 CH"CCH 3 ; subsequent CO insertion followed by reductive elimination leads to the formation of the corresponding thioesters. [62] The direct thiocarbonylation of a series of mono-and disubstituted allenes with thiols and carbon monoxide also gave the corresponding ␤,␥-unsaturated thioesters in 73-94% yields. This reaction requires catalytic quantities of Pd(OAc) 2 and triphenylphosphine in THF at 400 psi of CO and 100 °C for 48 h. Other palladium catalyst systems such as Pd 2 (dba) 3 иCHC1 3 -PPh 3 , Pd(PPh 3 ) 4 , and Pd(OAc) 2 -dppp are also effective for this reaction.…”