Polyvalent iodine in synthesis. 2. A new method for the preparation of aryl esters of dithiocarbamic acids

Abstract

The products were characterized by spectral and analytical means as summarized in the table. This reaction represents a general, simple, mild, and superior procedure for the direct synthesis of a variety of isopropylidene diarylmalonates 3 and isopropylidene alkylarylmalonates 5. Furthermore, since substituted isopropylidene malonates are readily hydrolyzed to carboxylic acids12 or converted to esters,13 this method represents an indirect, efficient preparation of -aryl carboxylic acids or their esters. Experimental SectionAll melt) ig points are uncorrected. NMR spectra were recorded at 60 MHz on a Varían EM-360 spectrometer with Me4Si in CDC13 as the internal standard, and IR spectra were recorded on a PE-683 spectrometer.Starting Materials. Meldrum's is commercially available or can be readily made by condensation of malonic acid with acetone. The necessary diaryliodonium salts 2 were prepared by standard procedures according to Beringer and co-workers.14 General Procedure for the Preparations of 3 and 5. Potassium metal (0.78 g, 20 mmol) was added to 20 mL of anhydrous tert-butyl alcohol. After reaction, 1.44 g (10 mmol) of Meldrum's acid (1) was added under nitrogen at 70 °C. To this solution was slowly added 20 mmol of the appropriate diaryliodonium salt 2. (For reaction of 4 with 2 the molar ratio of K to 4 to 2 was 1:1:1.) The resulting solution was stirred at 70 °C for several hours (see Table I) until it turned clear. After cooling, the solvent was removed, and to the residue were added 30 mL of methylene chloride and 10 mL of water. The organic layer was separated, washed successively with 10 mL of water, 10 mL of 5% aqueous NaHCOa, and 10 mL of water, and then dried over anhydrous MgS04. The methylene chloride was removed, to the residue was added 20 mL of petroleum ether, and the mixture was allowed to stand in a refrigerator overnight. The resulting crystals were collected by suction filtration and purified by recrystallization from benzene/hexane. All relevant data are summarized in the table.

MS and NMR investigation of bioactive quinazolones

“…According to a general literature procedure [9], the reaction of 1 with diphenyl iodonium chloride can furnish either the S-phenyl compound (6A) or the corresponding N-phenyl derivative (6B). …”

“…ESI (electrospray) does not enable to achieve efficient ionization. Ionization was accomplished in positive mode [9]. Compound 2 (Fig.…”

“…However, the predicted spectra (ChemWindow 3.0.2, 13 C NMR module, Softshell International) as well as the 15 N-1 H HMBC spectrum of our compound suggested the S-linkage (6A) rather than the N-linkage (6B) of the phenyl ring (crucial HMBC cross-peaks between (H-2V,6V) and (N-3) proving the N-linkage could not be detected). According to measured 13 C-NMR data (see Table 3), the chemical shift values for (C-2) carbon in each S-alkyl derivative (2)(3)(4)(5)(7)(8)(9) as well as in the S-benzyl derivative (10) of 2-mercapto-4(3H)-quinazolone (1) fall into the narrow range of 154.0 -156.5 ppm, while in the case of the starting 2-mercapto-4(3H)-quinazolone (1), the chemical shift value of the corresponding (C-2) carbon atom (d=174.8 ppm) is greater by 18.3 -20.8 ppm. In addition, literature data [12] of N-linked derivatives containing ''free'' -SH group (or the thiocarbonyl tautomer) showed the same value (d=174.7 ppm) for the chemical shift of (C-2) as in the case of 1; thus, the 155.0 ppm value for (C-2) of compound 6 also proves the S-linkage of the phenyl ring, e.g., the 6A structure.…”

α-Functionalization of Carbonyl Compounds Using Hypervalent Iodine Reagents

“…Similar conditions were later employed in the arylation of Meldrum's acid. [105] The arylation of diones was further investigated by Hampton and co-workers, who performed the phenylation of 2,4-pentanedione using sodamide in liquid ammonia. [106] It was possible to conduct this reaction on a multigram scale, furnishing the product in up to 64% yield.…”

Transition-Metal-Free C–S Bond Formation: Aqueous Synthesis of S-Aryl Dithiocarbamates by The use of Stable Arenediazonium Salts Mediated by Nano-Magnetic Supported Silica Sulfonic Acid

“…21 However, these methods have limited application because costly and toxic reagents are used. Other methods applied for the synthesis of S-aryl dithiocarbamates are the reaction of hypervalent iodine compounds with sodium salts of dithiocarbamic acids, 22 the reaction of certain organometallic reagents with tetramethyllitium disulfide, 23 coupling of sodium dithiocarbamates with aryl iodides catalyzed by CuI in the presence of a ligand in DMF(dimethyl formamide). 24 These methods suffer from one ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT 4 or more disadvantages such as the use of expensive and toxic reagents or difficulty in preparing the reagent.…”