P A-methyl

Few conclusions can be drawn for room-temperature films of copolymers or polymers. David et al.187) measured p g 0.02 for copolymers containing as little as 35% of the aromatic monomer. In contrast, MacCallum et al.188>189) found that p 0.2 for the excimer emission of PS and P(a-methyl S). The latter may be consistent with limited energy migration in pure PS, because the fraction of EFS chromophores in pure PS has recently been estimated to be about 40 %148). 

It is interesting that aldol-type condensation of tosylmethyl isocyanide (16) with aldehydes is catalyzed by the silver catalyst more stereoselectively than that catalyzed by the gold catalyst under the standard reaction conditions (Scheme 8B1.9) [26], Elucidation of the mechanistic differences between the gold and silver catalysts in the asymmetric aldol reaction of 16 needs further study. Oxazoline 17 can be converted to optically active a-alkyl-p-(A-methyl-amino)ethanols. 

The DAG methodology has been used recently in the synthesis of both isomers of oxisuran, as an application of a general route to the synthesis of o.p. a-methyl-sulfinyl ketones.132... 

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A chemoenzymatic synthesis of the P-a-methyl 2 -deoxynucleoside triphosphates 122 has been described which involves reaction of the 5 -0-(methylpho-sphonyl)-N-protected nucleosides with pyrophosphate in the presence of CDI. Removal of the base protection by treatment with penicillin amidase gave compounds 122 leaving the labile a-methylphosphonate intact. A number of 2 -deoxythymidine 5 -triphosphate and 3 -azido-2, 3 -dideoxythymidine 5 -tripho-sphate analogues (123) containing a hydrophobic phosphonate group have also been synthesised and evaluated as substrates for several viral and mammalian polymerases. Some y-ester (124) and y-amide (125) derivatives of dTTP and 3 -azido-2, 3 -dideoxythymidine 5 -triphosphate (AZTTP) were also synthesized and studied. The y-phenylphosphonate triphosphate 126 and its conjugation to biotin and fluorescein labels has also been described. 

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Other comparable ligands, but chiral, are those bearing o-substituted N,N-dimethylbenzylamine (P N = P(a-methyl-A,A-dimethylbenzylamine-o) Phi-n [33,43,44]. Solid state structures of transition metal complexes (e.g. of... 

ScHAUB, F., Nager, F., Schaer, H., Ziegler, W. and Lichtlen, P., a-Methyl-Dopa Therapeutische Erfahrungen bei Hypertonie und biochemische Untersuchungen zu seiner Wirkungsweise, Schweiz. Med. Wschr. 92 (20), 620 (1962). 

The above is a general procedure for preparing trialkyl orthophosphates. Similar yields are obtained for trimethyl phosphate, b.p. 62°/5 mm. triethyl phosphate, b.p. 75-5°/5 mm. tri-n-propyl phosphate, b.p. 107-5°/5 mm. tri-Mo-propyl phosphate, b.p. 83-5°/5 mm. tri-wo-butyl phosphate, b.p. 117°/5-5 mm. and tri- -amyl phosphate, b.p. 167-5°/5 mm. The alkyl phosphates are excellent alkylating agents for primary aromatic amines (see Section IV,41) they can also be ua for alkylating phenols (compare Sections IV,104-105). Trimethyl phosphate also finds application as a methylating agent for aliphatie alcohols (compare Section 111,58). 

Prepare a solution containing about 100 g, of potassium hypochlorite from commercial calcium hypochlorite ( H.T.H. ) as detailed under -Dimethylacrylic Acid, Section 111,142, Note 1, and place it in a 1500 ml. three-necked flask provided with a thermometer, a mechanical stirrer and a reflux condenser. Warm the solution to 55° and add through the condenser 85 g, of p-acetonaphthalene (methyl p-naphthyl ketone) (1). Stir the mixture vigorously and, after the exothermic reaction commences, maintain the temperature at 60-70° by frequent cooling in an ice bath until the temperature no longer tends to rise (ca. 30 minutes). Stir the mixture for a further 30 minutes, and destroy the excess of hypochlorite completely by adding a solution of 25 g. of sodium bisulphite in 100 ml. of water make sure that no hypochlorite remains by testing the solution with acidified potassium iodide solution. Cool the solution, transfer the reaction mixture to a 2-litre beaker and cautiously acidify with 100 ml. of concentrated hydrochloric acid. Filter the crude acid at the pump. 

Analysis Start with the a,p-unsaturated relationship as the alternative (the 1,2-di O) is no good at the start. After the first disconnection we have a methyl ketone which can come from an acetylene ... 

The operation of the nitronium ion in these media was later proved conclusively. "- The rates of nitration of 2-phenylethanesulphonate anion ([Aromatic] < c. 0-5 mol l i), toluene-(U-sulphonate anion, p-nitrophenol, A(-methyl-2,4-dinitroaniline and A(-methyl-iV,2,4-trinitro-aniline in aqueous solutions of nitric acid depend on the first power of the concentration of the aromatic. The dependence on acidity of the rate of 0-exchange between nitric acid and water was measured, " and formal first-order rate constants for oxygen exchange were defined by dividing the rates of exchange by the concentration of water. Comparison of these constants with the corresponding results for the reactions of the aromatic compounds yielded the scale of relative reactivities sho-wn in table 2.1. 

Various 4-, 5-, or 4,5-disubstituted 2-aryIamino thiazoles (124), R, = QH4R with R = 0-, m-, or p-Me, HO C, Cl, Br, H N, NHAc, NR2, OH, OR, or OjN, were obtained by condensing the corresponding N-arylthiourea with chloroacetone (81, 86, 423), dichloroacetone (510, 618), phenacyichloride or its p-substituted methyl, f-butyl, n-dodecyl or undecyl (653), or 2-chlorocyclohexanone (653) (Method A) or with 2-butanone (423), acetophenone or its p-substituted derivatives (399, 439), ethyl acetate (400), ethyl acetyl propionate (621), a- or 3-unsaturated ketones (691), benzylidene acetone, furfurylidene acetone, and mesityl oxide in the presence of Btj or Ij as condensing agent (Method B) (Table 11-17). 

In practice this reaction is difficult to carry out with simple aldehydes and ketones because aldol condensation competes with alkylation Furthermore it is not always possi ble to limit the reaction to the introduction of a single alkyl group The most successful alkylation procedures use p diketones as starting materials Because they are relatively acidic p diketones can be converted quantitatively to their enolate ions by weak bases and do not self condense Ideally the alkyl halide should be a methyl or primary alkyl halide... 

The melting point of indazole has been reported at various temperatures in the range of 145 to 149 °C. Indazole boils at 269-270 °C at 743 mmHg and 146 °C at 15 mmHg, can be readily sublimed on a water bath and is also steam-volatile. Its two A-methyl derivatives have similar melting points 1-methyl (106), m.p. 61 °C, 2-methyl (107), m.p. 56 °C, but they are easily separated by fractional distillation [(106), 120/15 (107), 141/15]. 

An E-Z discrimination between isomeric oxaziridines (27) was made by NMR data (69JCS(C)2650). The methyl groups of the isopropyl side chains in the compounds (27) are nonequivalent due to the neighboring carbon and nitrogen centres of asymmetry and possibly due to restricted rotation around the exocyclic C—N bond in the case of the Z isomer. The chemical shift of a methyl group in (Z)-(27) appears at extraordinarily high field, an effect probably due to the anisotropic effect of the p-nitrophenyl group in the isomer believed to be Z. 

Toluene is a notoriously poor electrical conductor even in grounded equipment it has caused several fires and explosions from static electricity. Near normal room temperature it has a concentration that is one of the easiest to ignite and, as previously discussed, that generates maximum explosion effects when ignited (Bodurtha, 1980, p. 39). Methyl alcohol has similar characteristics, but it is less prone to ignition by static electricity because it is a good conductor. Acetone is also a good conductor, but it has an equihbrium vapor pressure near normal room temperature, well above UFL. Thus, acetone is not flammable in these circumstances. 

RS- P-Aminoisobutyric acid (a-methyl-P-alanine) [10569-72-9] M 103.1, m 176-178 , 178-180 , 181-182 , R -(-)- isomer [144-90-1] m 183 , [a] -21 (c 0.43, HjO), pKes,(,) 3.7, pKEst(2) 10.2. Colorless prisms from hot H O, were powdered and dried in vacuo. The purity is checked by paper chromatography (Whatman 1) using ninhydrin spray to visualise the amino acid Rp values in 95% MeOH and n-PrOH/5N HCOOH (8 2) are 0.36 and 0.50 respectively. [Kupiecki and Coon Biochem Prep 7 20 7960 Pollack J Am Chem Soc 65 1335 7943.] The R-enantiomer, isolated from iris bulbs or human urine was crystd from H2O and sublimed in vacuo [Asen et al. J Biol Chem 234 343 7959]. The RS-hydrochloride was recrystd from EtOH/Et20 m 128-129 , 130° [Bbhme et al. Chem Ber92 1258, 1260, 1261 7959]. 

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