Palladium-Catalyzed C–H Monoalkoxylation of α,β-Unsaturated Carbonyl Compounds

Abstract

Contents1. General 2. Typical procedures to prepare the substrates 3. Typical procedure for the preparation of enol ether derivatives 4. Typical procedure for the introduction of amine substituent to the acrylic acid derivatives 5. Typical procedure for the introduction of phenyl substituent to the acrylic acid derivatives 6. References 7. NMR spectra of starting materials 8. NMR spectra of products GeneralThe 1 H NMR and 13 C NMR spectra were recorded by a JEOL JNM ECA-500 (500 MHz for 1 H NMR and 125 MHz for 13 C NMR), ECS-400 (400 MHz for 1 H NMR and 100 MHz for 13 C NMR), or AL-400 (400 MHz for 1 H NMR and 100 MHz for 13 C NMR) spectrometer. CDCl 3 , CD 2 Cl 2 or DMSO-d 6 was used as the solvent for the NMR measurements. The chemical shifts (δ) are expressed in part per million and internally referenced ( 1 H NMR: δ= 0.00; 13 C NMR; δ= 77.0 for CDCl 3 ; 1 H NMR: δ = 5.32;13 C NMR: δ = 53.3 for CD 2 Cl 2 ; 1 H NMR: δ = 2.49; 13 C NMR: δ = 39.5 for DMSO-d 6 ). The mass spectra (EI) were taken by a JEOL JMS Q1000GC Mk II Quad GC/MS. The IR spectra were recorded by a Brucker FT-IR ALPHA. The ESI high resolution mass spectra (HRMS) were measured by a Shimazu hybrid IT-TOF mass spectrometer. Typical procedures to prepare the substratesProcedure A: To a solution of acrylic acid (216 mg, 3.00 mmol) in DMF (5 mL) in a 50-mL round bottom flask equipped with a reflux condenser at 0 °C was added K 2 CO 3 (415 mg, 3.00 mmol). After 45 minutes, the alkyl chloride or alkyl bromide (2.50 mmol) was dropwise added, and the reaction mixture under an Ar atmosphere was stirred at 100 °C for 24 hours. The reaction mixture was cooled to room temperature, quenched with water (20 mL), and extracted with Et 2 O (20 mL × 2). The combined organic layers were dried over MgSO 4 , filtered, and concentrated in vacuo. The residue was purified by silica-gel column chromatography using hexane-EtOAc or hexane-Et 2 O as the eluent to give the corresponding alkyl acrylate.Procedure B: To a solution of acrylic acid (288 mg, 4.00 mmol), N,N'-dicyclohexylcarbodiimide (DCC, 1.03 g, 5.00 mmol), and the phenol derivative (4.00 mmol) in CH 2 Cl 2 (20 mL) in a 50-mL round bottom flask was added N,N-dimethyl-4-aminopyridine (DMAP, 50.0 mg, 409 μmol) at room temperature. The mixture was sitirred under an Ar atmosphere for 24 hours, quenched with water (20 mL), and extracted with Et 2 O (20 mL × 2). The combined organic layers were dried over MgSO 4 , filtered, and concentrated in vacuo. The residue was purified by silica-gel column chromatography using hexane-EtOAc as the eluent to give the corresponding alkyl acrylate. 4-Nitrobenzyl Acrylate 1The reaction was carried out using 4-nitrobenzyl bromide (540 mg, 2.50 mmol) according to typical procedure A. 4-Nitrobenzyl acrylate was obtained in 82% yield (425 mg, 2.05 mmol) after purification by silica-gel column chromatography (Hexane/EtOAc = 10/1).

Visible-Light-Promoted Selective Hydrogenation of Crotonaldehyde by Au Supported ZnAl-Layered Double Hydroxides: Catalytic Property, Kinetics, and Mechanism Investigation

“…α,β-Unsaturated alcohols form a group of important chemicals with the general formula of R–CHCHCH 2 OH. CH 3 CHCHCH 2 OHalso known as crotonyl alcoholis the simplest member of this group of compounds. , Crotonyl alcohol, also called butenol, is a colorless liquid with a special odor which has been used widely to synthesize butyl aldehyde, butanol, alcohol denaturants, herbicides, and plasticizers. , Currently, the α,β-unsaturated alcohol is synthesized by α,β-unsaturated aldehyde reduction, including both the traditional direct reduction method and the catalytic hydrogenation method. , The traditional direct method uses expensive reductants such as lithium aluminum hydride, sodium borohydride, aluminum isopropoxide, etc. in the process, and it has disadvantages such as high cost, harsh reaction conditions, contaminate generation, and challenges in product separation. − The new catalytic hydrogenation method has been drawing attention due to its low cost and environmental friendly nature. , The possible hydrogenation products of crotonaldehyde (CDE) include crotonyl alcohol (COL), butyraldehyde (BDE), ENOL, and butanol (BOL), which means there is competition for the hydrogenation on different double bonds.…”

“…CH 3 CH CHCH 2 OHalso known as crotonyl alcoholis the simplest member of this group of compounds. 1,2 Crotonyl alcohol, also called butenol, is a colorless liquid with a special odor which has been used widely to synthesize butyl aldehyde, butanol, alcohol denaturants, herbicides, and plasticizers. 3,4 Currently, the α,β-unsaturated alcohol is synthesized by α,β-unsaturated aldehyde reduction, including both the traditional direct reduction method and the catalytic hydrogenation method.…”

Applications of Sodium Nitrite in Organic Synthesis

“…Recently, Monguchi and Sajiki et al accomplished synthesis of a variety of enol ethers 146 via direct introduction of alkoxy groups into the β ‐position of alkene moieties of various α , β ‐unsaturated carbonyl compounds 144 through the Pd‐catalyzed Csp 2 –H monoalkoxylation using alcohols 145 in the presence of NaNO 2 (Scheme ) . Although several alcohols were compatible to this β ‐monoalkoxylation, bulkier alcohols afforded products in low yields due to lower reactivities attributed to the steric hindrance.…”

Palladium-Catalyzed Three-Component Silylalkoxylation of 1,3-Diene with Alcohol and Disilane via Oxidative Coupling

“…White and coworkers detailed the palladium-catalyzed intramolecular oxidative alkoxylation of terminal olefins using two equivalents of 1,4-BQ as a catalyst reoxidant and used this method to successfully synthesize oxygen-containing heterocycles (Figure B (II)) . Monguchi and Sajiki developed a method for the intermolecular oxidative alkoxylation of α,β-unsaturated carbonyl compounds using a palladium catalyst with more than two equivalents of AgOAc as the reoxidant (Figure B (III)) …”