Phenyl acetate amines with

Facilitated transport of penicilHn-G in a SLM system using tetrabutyl ammonium hydrogen sulfate and various amines as carriers and dichloromethane, butyl acetate, etc., as the solvents has been reported [57,58]. Tertiary and secondary amines were found to be more efficient carriers in view of their easy accessibility for back extraction, the extraction being faciUtated by co-transport of a proton. The effects of flow rates, carrier concentrations, initial penicilHn-G concentration, and pH of feed and stripping phases on transport rate of penicillin-G was investigated. Under optimized pH conditions, i. e., extraction at pH 6.0-6.5 and re-extraction at pH 7.0, no decomposition of peniciUin-G occurred. The same SLM system has been applied for selective separation of penicilHn-G from a mixture containing phenyl acetic acid with a maximum separation factor of 1.8 under a liquid membrane diffusion controlled mechanism [59]. Tsikas et al. [60] studied the combined extraction of peniciUin-G and enzymatic hydrolysis of 6-aminopenicillanic acid (6-APA) in a hollow fiber carrier (Amberlite LA-2) mediated SLM system. 

The reactivity of hydrido(ethoxo) complex 4 was examined (Scheme 6-15) [8]. Metatheses similar to those postulated for alcohol exchange (Eq. 6.5) occurred between HCl, LiCl, phenyl acetate or primary amines and yielded complexes 94. The reaction of 4 with cyclic anhydrides proceeded similarly to give iridium-assisted ring opening products 95. Heterocumulenes afforded the inserhon products 96 into the Ir-O bond. 

Initial theoretical studies focused on steps (1) and (2). Several model systems were examined with ab initio calculations.1191 For the reaction of methyl amine with methyl acetate, it was shown that the addition/elimi-nation (through a neutral tetrahedral intermediate) and the direct displacement (through a transition state similar to that shown in Figure 5a) mechanisms for aminolysis had comparable activation barriers. However, in the case of methyl amine addition to phenyl acetate, it was shown that the direct displacement pathway is favored by approximately 5 kcal/mol.1201 Noncovalent stabilization of the direct displacement transition state was therefore the focus of the subsequent catalyst design process. 

Lc yel crysts, mp 240° with decompn starts to blacken ca 200° sol in ben acet in sol in ligroin. Was prepd by treating silver salt of hexanitrodi phenyl amine with acetyl chloride. No refs to its expl props... 

Data for the reactions of several cyclic tertiary amines with phenyl, 4-nitro-phenyl and 2,4-dinitrophenyl acetates, at 25°C and ionic strength 1.0, appear in Table 40, and as a Bronsted plot in Fig. 20. The usual irregularities of such plots for nucleophilic attack are evident. Linear relationships between log k and pKa are generally found for groups of compounds of closely similar structure, as for the substituted pyridines in Fig. 20. The data for the two tricyclic amines fall on separate curves, and the points for imidazole clearly fall on neither of the first two sets of lines. The separate lines for the reactions of particular classes of nucleophile are approximately parallel, as is usually found. 

The condensation of an aldehyde, benzyl carbamate, and triphenyl phosphite, first described by Oleksyszyn et al., 25,26 affords a direct route to a-aminoalkylphosphonates 4 that are conveniently protected for subsequent reactions (Scheme 4). Since dealkylation of the quaternary phosphonium intermediate 3 is not possible in this case, formation of the pen-tavalent product 4 presumably involves activation of the solvent and formation of phenyl acetate. This method is useful for the synthesis of aliphatic and aromatic amino acid analogues. However, monomers with more elaborate side chains are often incompatible with the reaction conditions. The free amine can be liberated by treatment with HBr/AcOH or by hydrogenolysis after removal of the phenyl esters. The phosphonate moiety can be manipulated by ready exchange of the phenyl esters in alkaline MeOH and activation as described in Section 10.10.2.1.1. Related condensations with other trivalent phosphite derivatives have been reported. 27-30 ... 

The same author has reported chiral recognition of a-amino acids by native, anionic, and cationic a- and (3-cyclodextrins [17]. Both carboxylates and amines (monosubstituted as well as hexa- and heptasubstituted) were included in this study. The best results obtained were those from a combination of (S)- and (P)-AcTrp complexed by per-NH -[3-cyclodextrin with K=2,310 and 1,420 (1/mol). In the detailed study of chiral recognition of substituted phenyl-acetic acid derivatives by aminated cyclodextrins, these were found to be again only modest with respect to the enantioselection attained [18]. 

Reaction of (2-aminophenyl)-(4-bromophenyl)-methanone with methylsulfanylacetic acid ethyl ester and tert-butyl hypochlorite gives a corresponding sulfonium salt. This salt was transformed to initially to the betaine. Electrocyclic rearrangement of that transient intermediate leads, after rearomatization, to the homoanthranilic acid. Internal ester-amine interchange leads then to 4-bromophenyl-(3-(methylthio)indolin-7-yl)methanone. The thiomethyl group is then removed with Raney nickel to give 4-bromophenyl-(indolin-7-yl)methanone. Saponification of this intermediate affords the (2-amino-3-(4-bromobenzoyl)-phenyl)-acetic acid (Bromfenac). 

Ozonolysis of vinylpyrazine in methanol at — 30° furnishes pyrazine aldehyde in 73% yield.196 Vinylpyrazine undergoes a variety of addition reactions and pyrazylethyl derivatives of amines, ketones, ethyl phenyl acetate, phenylacetonitrile, and acetamide have been obtained.197-199 2-(2-Pyrazylethyl)cyclohexanone (42) has been prepared both by the condensation of vinylpyrazine with cyclohexanone in the presence of sodium metal and by interaction of vinylpyrazine with the pyrrolidine enamine of cyclohexanone followed by hydrolysis.200... 

Reactions of amines with substituted phenyl acetates are subject to a change in pathway as a function of basicity of the leaving phenoxide group. In the ammonolysis, hydrazinolysis, and imidazole-catalyzed hydrolysis of substituted phenyl acetates, both first- and second-order terms in amine are observed (Bruice and Mayahi, 1960 Bruice and Benkovic, 1964). Out of five phenyl acetate derivatives (p-NOg, m-N02, p-H, p-Cl, and p-CHs) the general-base term kz is observed with only the least acidic leaving groups, that is p-CHs, p-H, and p-Cl in the case of ammonolysis and hydrazinolysis, and p-CHj in the case of the imidazole reaction. Uncatalyzed k terms are observed with all... 

Called in Beil N-[3 Nitro-phenyl]-2,4,6-trinitrophenylendiamin-(l,3)l, H, N(0,N),--C H-NH-CjH NO,. Crysts(from et acet), mp 272°(decomp). Can be prepd either by heating 2,3,4,6-tetranitroaniline with 3 nitrobenzene in benzene or by fusing N-nitro-N-methy 1-2,4,6-trinitr 0-1,3 phe nylenedi amine with 3-nitroaniline at 110—120°. Its ezpl props were not reported... 

A bridged intermediate appears unlikely in the acetolysis of (338) since the solvolysis of the tertiary system (339) goes with neither aryl participation nor pheno-nium intermediates (cf. Section 7.3.3.). More direct evidence comes from the solvolysis of the chiral 2-methyl-2-phenyl-1-butyl system. Both the mesylate (340) and the amine (341) afford the product of phenyl migration, (342), with substantial racemization285. Similarly, the alkaline deamination of (343) yields largely racemic acetals (344)2S6 These stereochemical results clearly demonstrate the limits of phenonium ion intervention. 

Acrylic monomers are polymerized by carboxylic acids with tertiary aromatic amines (38), e.g., 4-N,N-(dimethylamino)phenyl-acetic acid ( ), presumably via a charge-transfer complex. 

Derivatization of amines with 2-methyl-3-keto-4-phenyl-2,3-dihydrofuran-2-yl acetate. 

To a solution of 2.10 g (7.8 mmol) of 10,10-dimcthy]-4-(l-oxopropenyl)-3.3-dioxo-3-thia-4-azatricy-clo[5.2.1.01 5]decane and 2.76 g (17.2 mmol) of 2-methyl-2-(2-nitroethyl)-l,3-dioxolane in 210 mL of benzene at 25 C under nitrogen is added 2.54 mL (23.4 mmol) of phenyl isocyanate followed by 2.40 mL (17.2 mmol) of triethylamine. After 24 h the same amount of phenyl isocyanate and amine are added, and stirring continued for 24 h. The mixture is diluted with 300 mL of ethyl acetate, washed with 300 mL of water and dried. The solvent is removed in vacuo and the residue purified by chromatography with ethyl acctatc/hexane 35 65 as eluant. The major isomer, with 5.S-configuration, is obtained as a gum yield 2.73 g (85%) [a] +204 (c = 10.5, CHC13). 

Base-catalyzed anhydride-epoxide reactions have been found to have greater selectivity toward diester formation. Shechter and Wynstra (8) showed that equal molar amounts of acetic anhydride and phenyl glycidyl ether with either potassium acetate or tertiary amines as a catalyst reacted very selectively. They proposed the following reaction mechanism for the acetate ion catalyzed reaction ... 

---