Methyl phenylthioacetate

One of the most important characteristics of IL is its wide temperature range for the liquid phase with no vapor pressure, so next we tested the lipase-catalyzed reaction under reduced pressure. It is known that usual methyl esters are not suitable for lipase-catalyzed transesterification as acyl donors because reverse reaction with produced methanol takes place. However, we can avoid such difficulty when the reaction is carried out under reduced pressure even if methyl esters are used as the acyl donor, because the produced methanol is removed immediately from the reaction mixture and thus the reaction equilibrium goes through to produce the desired product. To realize this idea, proper choice of the acyl donor ester was very important. The desired reaction was accomplished using methyl phenylth-ioacetate as acyl donor. Various methyl esters can also be used as acyl donor for these reactions methyl nonanoate was also recommended and efficient optical resolution was accomplished. Using our system, we demonstrated the completely recyclable use of lipase. The transesterification took place smoothly under reduced pressure at 10 Torr at 40°C when 0.5 equivalent of methyl phenylthioacetate was used as acyl donor, and we were able to obtain this compound in optically pure form. Five repetitions of this process showed no drop in the reaction rate (Fig. 4). Recently Kato reported nice additional examples of lipase-catalyzed reaction based on the same idea that CAL-B-catalyzed esterification or amidation of carboxylic acid was accomplished under reduced pressure conditions. ... 

Boron enolates of thioglycolates. Esters do not form boron enolates because of the low acidity of the a-protons. However, methyl phenylthioacetate (2) forms a boron enolate on treatment with Hunig s base and dibutylboryl triflate, and this enolate undergoes aldol reactions with aldehydes with high syn-diastereoselectiv-ity.1... 

Methyl a-chloro-a-phenylthioacetate, C6H5SCH(Cl)COOCH3 (1). The reagent is most conveniently prepared by NCS chlorination of methyl phenylthioacetate. 

The lipase-catalysed enantioselective acylation of allylic alcohols in an ionic liquid solvent was demonstrated by Itoh et al. [16] (Fig. 7.7). They found that the acylation rate was strongly dependent on the counter anion of the imidazolium salt, while the lipase-catalysed acylation proceeded with high enantioseleclivity in all ionic liquid tested. Good results were obtained when the reaction was carried out in [bmimT [PFg ] or [bmun" ][BF ]. Other examples of kinetic resolution of allylic alcohols catalysed by lipases in ionic liquids were also reported by these authors [71, 72]. The transesterification of 5-phenyl-l-penten-3-ol under reduced pressure at 27 hPa and 40°C was carried out using methyl phenylthioacetate as acyl donor in [bmim+] [PF ] and [bdmim ][BF ], for obtaining the corresponding acylated compound in optically pure form [71], The acetylation of methyl mandelate catalysed by immobilised P5L in [bdmim ][BF ] is another example reported by these authors about the successful application of ionic liquids as reaction media in racemic resolutions... 

Preparative Methods by chlorination of methyl phenylth-ioacetate using sulfuryl chloride or 7V-chlorosuccinimide (NCS) methyl phenylthioacetate (16.8 g) is stirred with powdered NCS (13.3 g) in CCI4 at rt for 10 h, the mixture filtered, the filtrate evaporated, and the residue distilled using a short Vigreux column. ... 

Hydroxy-a-phenylthio-acids and their methyl esters can be prepared by condensations between carbonyls and the bis-anionic species (13) from phenyl-thioacetic acid or the monoanion (14) from methyl phenylthioacetate respectively. Yields are often excellent although the bis-anion (13) is less reactive, failing to condense with 2-methylcyclohexanone or acetophenone. With enones, (13) undergoes [1,2] addition by contrast the monanion (14) adds in a Michael fashion. 

Scheme 9.1 describes reactions with several lithiated compounds, including dichloromethane, dichloromethyl methyl ether, phenylthiomethyl methyl ether, and phenylthioacetals. Compare the structure of these reagents and the final products for these reactions. Develop a mechanistic outline that encompasses these reactions. Discuss the features that these reagents have in common with one another and with carbon monoxide. 

The telomer 138 is a good building block for the 10-membered skeleton of diplodialide (166) [61]. The terminal double bond in 138 is oxidized with PdCl2/CuCl/02 to the methyl ketone 163 and converted to 164. The phenylthioacetate 165 is prepared and its cyclization gives 9-decanolide (166). 

The sulfur monomeric radical cations (X-S -Y-COOH) were formed from direct ionization of the sulfur atom in parental aromatic carboxylic acids. These X-S -Y-COOH were found to decay by three competitive pathways (i) fragmentation via the cleavage of the C-S bond producing thiyl-type radicals XS, (ii) deprotonation from the methyl/methylene groups adjacent to the sulfur producing a-(alkylthio)alkyl radicals, and (iii) decarboxylation producing C-centered radicals (for phenylthioacetic acid, vide Scheme 6). The efficiency of each pathway is dependent on the structure of the aromatic carboxylic acid studied. 

METHYL KETONES Chromic acid. Ethyl a-phenylsulflnylacetate. Lithium acetylide. Lithium diethylamide-Hexamethylphophoric triamide. S-(2-MethoxyallyI)-N,N-dimeth-yldithiocarbamate. a-Methoxyvinyllithium. Phenylthioacetic acid. Potassium tetra-carbonylhydridoferrate. Silver(II) oxide. Trimethylaiuminium. 

Methyl a-chloro-a-phenylthioacetate (2) reacts with silyl enol ethers (1) in the presence of Lewis acids, typically zinc bromide in catalytic quantities or titanium(IV) chloride in stoichiometric quantities, to give the 1,4-dicarbonyl products (3) (eq 1). The reaction is regiospecific (eqs 2 and 3), and /-selective with the silyl dienol ether (4) (eq 4). ... 

---