Hydantoin, 5-phenyl

Hydantoin, 5,5-diaryl-2,4-dithio-methylation, 5, 444 Hydantoin, 1,3-divinyl-polymers, 1, 280 Hydantoin, 5-methylene-polymers, 1, 280 Hydantoin, 5-phenyl-2-thio-tautomerism, 5, 370 Hydantoin, thio-... 

Mass spectral fragmentation patterns of alkyl and phenyl hydantoins have been investigated by means of labeling techniques (28—30), and similar studies have also been carried out for thiohydantoins (31,32). In all cases, breakdown of the hydantoin ring occurs by a-ftssion at C-4 with concomitant loss of carbon monoxide and an isocyanate molecule. In the case of aryl derivatives, the ease of formation of Ar—NCO is related to the electronic properties of the aryl ring substituents (33). Mass spectrometry has been used for identification of the phenylthiohydantoin derivatives formed from amino acids during peptide sequence determination by the Edman method (34). 

The reaction mixture is removed and about half of the liquid evaporated, an oil separating during the process. The mixture is acidified with concentrated hydrochloric acid and extracted with two 100 cc portions of ether. The extracts, which contain the 5-phenyl-5-(2-thienyOhydantoin, are combined and the combined ether extracts are shaken with two 25 cc portions of 5% potassium hydroxide solution. The alkaline solution, which dissolves the 5-phenvl-5-(2-thienvl)hydantoin to form the potassium salt thereof, is acidifed with hydrochloric acid and heated to expel ether. 

S ORTHO AND EFFECT AND HAMMETT S (carbon(W)DIOXIDE OR carbon(W)DISULnDE) AND CATALY NOT ACID S HYDANTOIN AND (METHYL OR ETHYL) NOT (VINYL OR PHENYL)... 

Hydantoin analogs in this series 72) were prepared. Most of these compounds, however, were found less active as anticonvulsants than the corresponding phenyl derivatives. Only a few were found to have the same order of activity as 5,5-diphenylhydantoin. 

Answer D. Phenyl hydantoins decrease the activity of vitamin K, which is required for the y-carboxylation of coagulation factors (11, VII, IX, X), as well as proteins C and S. 

Tertiary amines were amongst the first initiators of NCA polymerisation which had been described in the literature and it seems that the polymerisation of all the known NCA s may be accomplished by their action. Wessely (77) reported in 1925 that glycine and phenyl alanine NCA s are readily polymerised in pyridine at ambient temperatures, and in the following paper (72) he reported a similar polymerisation of sarcosine NCA. The polypeptides produced by this initiator apparently formed cyclic polymers since no terminal end groups could be detected 41). It is significant that appreciable quantities (a few %) ot 3-acetic-hydantoin derivatives were found in the polymers formed from glycine and phenyl alanine NCA s but none was detected in the polymerised sarcosine NCA (72). This evidence suggests that the mechanisms of polymerisation initiated by aprotic bases may be different for the non-N-substituted NCA and the N-substituded anhydrides. 

In contrast to acyl amino acids (pKa > 30) or amides, most 5-monosubstituted hydantoins racemize comparatively easily phenyl-substituted ones even racemize spontaneously at slightly alkaline conditions as their pK.d is around 8 (Kato, 1987). Under spontaneous or enzymatic racemization (Pietzsch, 1990), racemic hydantoins with the help of enantioselective d- or L-hydantoinases and the respective carb-... 

The search for other amino acid-based catalysts for asymmetric hydrocyanation identified the imidazolidinedione (hydantoin) 3 [49] and the e-caprolactam 4 [21]. Ten different substituents on the imide nitrogen atom of 3 were examined in the preparation, from 3-phenoxybenzaldehyde, of (S)-2-hydroxy-2-(3-phenoxy-phenyl)acetonitrile, an important building block for optically active pyrethroid insecticides. The N-benzyl imide 3 finally proved best, affording the desired cyanohydrin almost quantitatively, albeit with only 37% enantiomeric excess [49]. Interestingly, the catalyst 3 is active only when dissolved homogeneously in the reaction medium (as opposed to the heterogeneous catalyst 1) [49]. With the lysine derivative 4 the cyanohydrin of cyclohexane carbaldehyde was obtained with an enantiomeric excess of 65% by use of acetone cyanohydrin as the cyanide source [21]. 

The following were introduced into 288 ml of phenyl oxide 96.10 grams of 5,5-dimethyl-hydantoin, 170.86 grams of 2-nitro-5-chloro trifluoromethylbenzene and 89.40 grams of cupric oxide. The mixture was heated to 190°C for about 23 hours, then cooled to 20°C and filtered. The residue was characterized in the phenyl oxide filtrate by thin layer chromatography. The analytical results obtained for these 5 examples were identical to those obtained and indicated in French Patent No. 2,329,276. 

By the process of purification, 4.3 g of 5-phenyl-5-(2-thienyl)hydantoin is obtained, and from the ether layer, 2.2 g of unreacted ketone. The yield of the 5-phenyl-5-(2-thienyl)hydantoin is about 56%. The melting point of the purified 5-phenyl-5-(2-thienyl)hydantoinis about 256°C to 257°C. 

The racemic 2-azabicyclo[2.2.1]heptane-3-carboxylic acid was obtained by alkaline hydrolysis (24 h reflux in 4 N NaOH/MeOH 3/1 yield 78%) of the 4-phenyl-2,4-diazatricyclo[5.2.1.02-5]decane-3,5-dione-(l)- hydantoin obtained... 

The hydantoins (116 and 117) have been prepared from DL-j8-ferrocenyl-a-alanine and N - ferrocenyl methyl-AT-(a-carbethoxy-benzyl)urea, respectively.68 The Friedel Crafts reaction of ferrocene and 2-pyrroylchloride gave the ketone (118).112,113 The polarographic half-wave potentials of 118 and other related ferrocenes were measured113 and it was concluded that the ferrocene radical was more electropositive than the phenyl radical. 

High velocities of chemical racemization have only been observed for d,l-5-phenyl- and D,L-5-p-hydroxy-phenylhydantoin, because of the resonance stabilization by the 5-subshtuent, while all other hydantoins take many hours to racemize... 

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