Arylation of Allyl Alcohols in Organic and Aqueous Media Catalyzed by Oxime‐Derived Palladacycles: Synthesis of β‐Arylated Carbonyl Compounds

Abstract

A 4-hydroxyacetophenone oxime-derived palladacycle catalyzes the Mizoroki-Heck reaction of allyl alcohols with aryl iodides, bromides, and chlorides in aqueous and organic solvents. The reaction takes place in the presence of dicyclohexylmethylamine or cesium carbonate as bases, the addition of tetrabutylammonium bromide (TBAB) as additive for aryl bromides and chlorides being necessary. Under these reaction conditions, b-arylated aldehydes and ketones are mainly obtained using a rather low loading of palladium (0.1-1 mol %). Similar catalytic activity is shown by a Kaiser oxime resin-derived palladacycle, which allows one to perform recycling and reusing experiments with low Pd leaching. The high regio-and chemoselectivity observed supported that these palladacycles, working as a source of Pd(0) species, operates mainly through a neutral mechanism. This methodology has been applied to the synthesis of important b-arylated carbonyl compounds, such as 4-phenylbutan-2-one, 4-(4-hydroxyphenyl)butan-2-one, dihydrochalcones, the anti-inflamatory nabumetone, and the fragance blilial . g-Arylation is observed in the reactions of allyl alcohol and but-3-en-2-ol with 2-iodoaniline giving mainly the corresponding quinolines. The same tendency is observed in the case of 1,1-dimethylallyl alcohol affording either g-arylated alcohols or (E)-1-arylisoprenes.

Regioselective Heck Reaction of N‐Vinylphthalimide: A General Strategy for the Synthesis of (E)‐N‐Styrylphthalimides and Phenethylamines

“…Initial studies were performed on the coupling of 4-bromoacetophenone as an activated aryl bromide and N-vinylphthalimide (1), under the previously reported reaction Heck conditions for aryl bromides, [12,13] with dicyclohexylmethylamine as base, tetra-n-butylammonium bromide (TBAB) [14] as additive, and palladacycle 4 (1 mol% Pd) as catalyst in aqueous N,N-dimethylacetamide (DMA) at 120 8C giving no conversion (Scheme 1 and Table 1, entry 1). However, full conversion and high regio-and diasteroselectivity were observed in DMF as solvent affording product 6a in 14 h reaction time with the E-configuration in 76% yield after recrystallization (Table 1, entry 2).…”

“…We have recently studied the Heck reaction [9] of electron-rich alkenes using Cy 2 NMe as base and 2 or palladacycles 3, 4, or 5 [10] (Figure 3) as catalysts under phosphine-free conditions. Thus, styrenes [11] allylic alcohols, [12] and acrolein diethyl acetal [13] react with aryl halides giving mainly arylation at the terminal position of the double bond according to a neutral mechanism. Here, we describe the appropriate reaction conditions for the regioselective Heck arylation of N-vinylphthalimide (1) at the b-position.…”

Oxime‐Derived Palladacycles: Applications in Catalysis

“…By using dimer 1 e or supported complex 4 (0.1–1 mol % Pd), dicyclohexylmethylamine as base, and TBAB as an additive, in water for aryl iodides (54–85 %) and in aqueous DMA for aryl bromides (33–82 %), γ‐arylation occurred according to the aforementioned mechanism, giving the corresponding β‐arylated aldehydes and ketones in a highly regio‐ and chemoselective manner . However, when Pd(OAc) 2 was used as the catalyst, much lower yields were obtained than with palladacycles.…”

ChemInform Abstract: Oxime‐Derived Palladacycles: Applications in Catalysis

“…[44][45][46][47] By using dimer 1e or supported complex 4 (0.1-1 mol % Pd), dicyclohexylmethylamine as base, and TBAB as an additive, in water for aryl iodides (54-85%)a nd in aqueous DMA for aryl bromides (33-82 %), g-arylation occurred according to the aforementioned mechanism, giving the corresponding barylated aldehydes and ketones in ah ighly regio-and chemoselectivem anner. [48] However,w hen Pd(OAc) 2 was used as the catalyst, much lower yields were obtained than with palladacycles. Representative examples are the synthesis of the anti-inflammatory drug nabumetone and the fragrance b-lilial (Scheme 7).…”

“…For the synthesis of quinolines from 2-iodoaniline, allylic alcohols [48] or MBH adducts [105] have been used. In the former case, Cy 2 NMe was used as base, TBAB as additive, and DMA/ H 2 O( 4:1) as solvents at 120 8C( Scheme 34 a).…”