Simple, Copper(I)-Catalyzed Oxidation of Benzylic/Allylic Alcohols to Carbonyl Compounds: Synthesis of Functionalized Cinnamates in One Pot

Abstract

IR spectra were recorded on a Bruker Tensor 37 (FTIR) spectrophotometer. 1 H NMR spectra were recorded on Bruker Avance 400 (400 MHz) spectrometer at 295 K in CDCl 3 ; chemical shifts (δ in ppm) and coupling constants (J in Hz) are reported in standard fashion with reference to either internal standard tetramethylsilane (TMS) (δ H =0.00 ppm) or CHCl 3 (δ H = 7.25 ppm). 13 C NMR spectra were recorded on Bruker Avance 400 (100 MHz) spectrometer at RT in CDCl 3 ; chemical shifts (δ in ppm) are reported relative to CHCl 3 [δ C = 77.00 ppm (central line of triplet)]. In the 13 C NMR, the nature of carbons (C, CH, CH 2 and CH 3 ) was determined by recording the DEPT-135 spectra, and is given in parentheses and noted as s = singlet (for C), d = doublet (for CH), t = triplet (for CH 2 ) and q = quartet (for CH 3 ). In the 1 H-NMR, the following abbreviations were used throughout: s = singlet, d = doublet, t = triplet, q = quartet, qui = quintet, m = multiplet and br. s = broad singlet. The assignment of signals was confirmed by 1 H, 13 C CPD and DEPT spectra. High-resolution mass spectra (HR-MS) were recorded on an Agilent 6538 UHD Q-TOF using multimode source. All small scale dry reactions were carried out using Schlenk tube technique. Reactions were monitored by TLC on silica gel using a mixture of petroleum ether and ethyl acetate as eluents. Reactions were generally run under an argon or nitrogen atmosphere. Solvents-petroleum ether with a boiling range of 60 to 80 C, ethyl acetate, dichloromethane and diethyl ether-were distilled prior use. Diethyl ether and 1,4dioxane were dried over benzophenone/sodium and DMF was dried over calcium hydride. 1,10phenanthroline and aromatic aldehydes were purchased from local sources and used as received. CuI and K 3 PO 4 were purchased from sigma-Aldrich. Acme's silica gel (60-120 mesh) was used for column chromatography (approximately 20 g per one gram of crude material). General Procedure-1 [For the inert oxidation of alcohols to carbonyl compounds; GP-1(method A)]:In an oven dried Schlenk tube, were added alcohol 1 (69.0-199.5 mg, 0.5 mmol), CuI (10 mol%) and 1,10-Phenanthroline (20 mol%) and K 3 PO 4 (2 mmol) followed by the addition of dioxane (2 mL) at room temperature under a nitrogen atmosphere. The stirred reaction mixture was heated in an oil bath at 80 C for 24-48 h. Progress of the reaction was monitored by TLC till the reaction is completed. Then, the reaction mixture was cooled to room temperature, quenched with aqueous NH 4 Cl solution and then extracted with CH 2 Cl 2 (3  10 mL). The organic layer was washed with saturated NaCl solution, dried (Na 2 SO 4 ), and filtered. Evaporation of the solvent under reduced pressure and purification of the crude material by silica gel column chromatography (petroleum ether/ethyl acetate) furnished the aldehyde/ketone 2 (58-92%).Compounds 1a & 2a, 1c & 2c, [1] 1b & 2b, [2] 1d & 2d, [3] 1e & 2e, [4] 1f-n [5] & 2f, [6] 2g, [7] 2h, [8] 2i, [9] 2j, [10] 2k, [11] 2l, [12] 2m, [13] 2n, [14] 1o & 2o, 1z & 2z, 1ad, 2...

A Domino Palladium-Catalyzed Cyclization: One-Pot Synthesis of 4b-Alkyl-10-phenyl-4b,5-dihydroindeno[2,1-a]indenes via Carbopalladation Followed by C–H Activation

“…In continuation of our research interests on the development of domino transformations, we envisioned that the 1-bromo-2-isopropenylbenzenes in the presence of an appropriately designed palladium-catalyst would undergo first intermolecular insertion onto the triple bond of internal alkynes followed by a second intramolecular insertion into the olefinic bond (i.e., the first cyclization) that leads to carbo-palladation of indenes. Further, we envisaged that with an appropriate palladium-catalyst, these carbo-palladized indenes would in turn be feasible for the final cyclization (i.e., the second cyclization) with the aromatic ring of internal acetylenes through C–H activation to furnish the novel 4b-alkyl-10-phenyl-4b,5-dihydroindeno­[2,1- a ]­indenes 3 .…”

Tandem-, Domino- and One-Pot Reactions Involving Wittig- and Horner-Wadsworth-Emmons Olefination

“…One-pot oxidation-Wittig olefination reactions are also quite common [40,, especially when the carbonyl component is labile [89,97]. Often, the oxidant of choice is MnO 2 [40,[43][44][45][46][79][80][81][82][83][84][85][86][87][88][89][90][91][92][93][94][95][96][97], although a number of reactions are known where transformations were carried with air oxygen using metals and metal oxides as catalysts [72][73][74][75][76][77][78]. As many Wittig-and HWE reactions tolerate metal catalysts, this allows the running of Wittig/HWE reactions in combination with metal catalyzed cross coupling reactions and olefinations such as Heck [114][115][116][117][118][119][120][121][122][123], Suzuki [111]…”