4- Acylamino-3-hydroxy

Durch die Reaktion von 1,3,4-Oxadiazolium-Salzen mit 5-Hydroxy-1,3-oxazolen fiber eine isolierbare ringoffene Zwischenstufe konnen in guten Ausbeuten 4-Acylamino-3-hydroxy-pyrazole hergestellt werden748 ... 

The parent compound and a set of monosubstituted bis(acylamino)diarylspiro-X4-sulfanes (360 X = H, Me, MeO, Cl, NO2) undergo hydrolysis to the corresponding sulfoxides (361). The probable mechanism involves rate-determining cleavage of one of the S—N hypervalent bonds in the spiro ring with simultaneous proton transfer to the nitrogen atom. The hydroxide ion which is formed thereby then attacks the sulfur atom in a fast step to form a diaryl(acylamino)hydroxy-k4-sulfane (362), which is converted into the sulfoxide (361) (Scheme 47). ... 

Br prevents side reactions and makes BiBr3 a better Lewis acid catalyst, which is in accordance with our work BiBr3 affords only Ritter reaction products in the high dielectric constant solvent CH3CN, while BiCl3 originates a mixture of both v7 -/V-acylamino-hydroxy compounds and chlorohydrins. 

The Ritter reaction has been recently reported to be catalyzed by BiX3 salts (Equation 40). Starting from epoxides this reaction leads in one step to vic-acylamino-hydroxy compounds in high yields (71-94%). In the case of 5a-6a-epoxide of steroids, the reaction has resulted in the formation of 6P-acylamido-5a-steroids [83]. 

The 5-acylamino-THISs react with alkynes in a way already exemplified for 5-hydroxy-THISs. Pyrroles are formed under elimination of isothiocyanate (Scheme 29) (37). 5-Acylamino-THISs are readily bromi-nated in the 4-position (21). 

Benzo[6]thiophene, 2-acetyl-3-hydroxy-synthesis, 4, 892 Benzo[6]thiophene, 2-acyl-synthesis, 4, 918 Benzo[6]thiophene, 3-acyl-synthesis, 4, 918- 19 Benzo[6]thiophene, acylamino-synthesis, 4, 815 Benzo[6]thiophene, alkenyl-synthesis, 4, 917 Benzo[6]thiophene, 2-alkoxy-synthesis, 4, 929 Benzo[6]thiophene, 3-alkoxy-synthesis, 4, 929 Benzo[6]thiophene, 4-alkoxy-synthesis, 4, 930 Benzo[6]thiophene, 2-alkyl-synthesis, 4, 877-878 Benzo[6]thiophene, 2-alkylthio-synthesis, 4, 931 Benzo[6]thiophene, 2-amino-diazotization, 4, 810 reactivity, 4, 797 stability, 4, 810 synthesis, 4, 869, 924-925 tautomerism, 4, 38 Benzo[6]thiophene, 3-amino-cycloaddition reactions, 4, 68 synthesis, 4, 109, 881, 925 Benzo[6]thiophene, 4-amino-synthesis, 4, 925 Benzo[6]thiophene, 5-amino-synthesis, 4, 925 Benzo[6]thiophene, 7-amino-synthesis, 4, 925 Benzo[6]thiophene, 3-t-amyl-synthesis, 4, 915 Benzo[6]thiophene, 2-aryl-synthesis, 4, 881... 

Cephalosporanic acid, 3 -deacetoxy-, 7, 289 Cephalosporin, 3 -deacetoxy-absorption, 7, 293 synthesis, 7, 293 Cephalosporin, 3,4-dihydro-synthesis, 7, 292 Cephalosporin, 7a-hydroxy-synthesis, 7, 290 Cephalosporin C, 7, 288 as pharmaceutical, 1, 152 total synthesis, 7, 294 Woodward s total synthesis, 7, 294 Cephalosporin C, deacetoxy-synthesis, 7, 292 Cephalosporins, 7, 267, 285-298 7-acylamino substituent configuration, 7, 290 analogues synthesis, 7, 288 as antibiotics, 2, 519 3, 1038 application, 7, 296... 

Thiazole, 2-acetylamino-4-methyl-alkylation, 6, 256 Thiazole, 2-acylamino-4-hydroxy-synthesis, 6, 297 Thiazole, 5-alkoxy-cleavage, 6, 289 synthesis, 6, 302 Thiazole, 2-alkyl-A7-alkylation, 6, 253 hydrogen exchange, 6, 276 methylation, 6, 253 quatemization, 6, 253-254 reactions, S, 88 Thiazole, 4-alkyl-A7-alkylation, 6, 253 methylation, 6, 253 quatemization, 6, 253-254 Thiazole, 5-alkyl-A7-alkylation, 6, 253 methylation, 6, 253 Thiazole, 2-alkylamino-tautomerism, 6, 248 Thiazole, 4-alkyl-2,5-dimethyl-quatemization, 6, 253-254 Thiazole, 2-alkylthio-reactions, S, 103 rearrangement, 5, 103 6, 291 Thiazole, 3-allyl-4-hydroxy-2-imino-synthesis, 6, 297 Thiazole, 2-allyloxy-rearrangement, 6, 289 Thiazole, 2-amino-diazo coupling, 6, 257 nitration, 6, 255... 

In their acidity, basicity, and the directive influence exerted on electrophilic substitution reactions in benzenoid nuclei, acylamino groups show properties which are intermediate between those of free amino and hydroxyl groups, and, therefore, it is at first surprising to find that the tautomeric behavior of acylaminopyridines closely resembles that of the aminopyridines instead of being intermediate between that of the amino- and hydroxy-pyridines. The basicities of the acylaminopyridines are, indeed, closer to those of the methoxy-pyridines than to those of the aminopyridines, the position of the tautomeric equilibrium being determined by the fact that the acyl-iminopyridones are strong bases like the iminopyridones and unlike the pyridones themselves. Thus, relative to the conversion of an... 

Pyrrole nucleus, in basicity scale, 71 as model in resonance theory. 69 Pyrroles, from 5-acylamino-THlSs. 14 from 5-hydroxy-THISs, 9 from 4-substituted-5-hydroxythiazoles,... 

Application of the Ritter reaction conditions on y-hydroxy-a,P-alkynoic esters, 102, produced ethyl 5-oxazoleacetates 103 or y-A-acylamino-P-keto ester 104 by reaction with aryl or alkyl nitriles respectively. The y-A-acylamino-P-keto ester 104 can also be transformed into oxazole derivatives using an additional step involving POCI3 <06TL4385>. 

The two-step activation of oxazolidinones is depicted in Fig. 8.26. Hydrolysis yields an A-(l -hydroxy alkyl) derivative, which breaks down to liberate the peptide or A-acylamino acid (Fig. 8.26, Reactions a and b). Since oxazolidinones are prepared by the condensation of a peptide and an aldehyde (Fig. 8.26, Reaction c), the reverse reaction (i. e., one-step activation) cannot be excluded. Examples of this type of prodrug are provided by a series of oxazolidinones of the general structure 8.190 (R = PhCH20 R = H, Me, i-Pr, or PhCH2 R" = H, Me, or Ph Fig. 8.26) [248]. In phosphate buf-... 

There are many reports describing the preparation of various butyrolac-tones from AAs. When r-butyl 2-dibenzylaminoacetate in the form of its Li-enolate was treated with (5)-0-benzyllactic aldehyde, a mixture of four diastereoisomeric hydroxy-AAs was obtained. After separation and further treatment, three lactones were obtained (Scheme 17) (87T2317). Similar compounds were obtained from a-acylamino-y-keto acids after cycliza-tion (75CC905). 

Silyl-substituted diazoketones 29 cycloadd with aryl isocyanates to form 1,2,3-triazoles 194 (252) (Scheme 8.44). This reaction, which resembles the formation of 5-hydroxy-l,2,3-triazoles 190 in Scheme 8.43, has no analogy with other diazocarbonyl compounds. The beneficial effect of the silyl group in 29 can be seen from the fact that related diazomethyl-ketones do not react with phenyl isocyanate at 70 °C (252). Although the exact mechanistic details are unknown, one can speculate that the 2-siloxy-1-diazo-1-alkene isomer 30 [rather than 29 (see Section 8.1)] is involved in the cycloaddition step. With acyl isocyanates, diazoketones 29 cycloadd to give 5-acylamino-l,2,3-thiadiazoles 195 by addition across the C=S bond (252), in analogy with the behavior of diazomethyl-ketones and diazoacetates (5). 

Deacetylation of 4-[(o-acetoxy)benzylidene]-2-phenyl-5(47/)-oxazolone also immediately affords 602. The starting oxazolone was obtained by cyclodehydration of the corresponding cinnamic acid precursor or by condensation of hippuric acid with 2-acetoxybenzaldehyde in the absence of base. In examples using 2-hydroxy-acetophenone, 4-methyl-3-(acylamino)coumarins are obtained. ... 

N-acylamino acids does not appear to have been studied previously. In solution, N-acyl-N-nitroso-a-amino acids are moderately stable to weak bases, such as triethylamine or sodium carbonate, but are decomposed rapidly at 0° to expel nitrogen on addition of sodium hydroxide (43). For example, treatment of N-nitroso-N-benzoyl-D,L-pheny1-alanine LXIIb with an aqueous sodium hydroxide solution at 0 gives benzoic acid and 1-hydroxy-3-phenylpropanoic acid LXVa in a 93% yield. The facile base-catalysed formations of a-hydroxy acids LXV are a general reaction and probably occur by intramolecular attack as shown in LXII->LXIII->LXIV. Oxadiazolone LXIV can decompose by various possible pathways to give LXV among which the carbonium ion pathway is least likely. 

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