5-Acylamino-4-aryl

Oxazoles and 4,5-dihydrooxazoles can be transformed into quinolines. For instance, 5-(o-acylamino-aryl)oxazole-4-carboxylic esters 104, made from benzoxazinones 103 and isocyanoacetic ester, are converted into 3-aminO 4-hydroxy-2-quinolones 105 in an acid medium [109]. 

Disubstituted benzimidazoles 10 are also obtained by Cu-mediated amination of (2-acylamino)aryl iodides with arylamines in the presence of L-proline and K2CO3 followed by add-catalyzed cydization [417]. 

An analogous protocol of Pd-catalyzed amination of (2-acylamino)aryl bromides with arylamines and subsequent ring-closure of the intermediarily formed N-aryl-N -acyl-o-phenylenediamines 11 leads to N-arylbenzimidazoles (10, = Ar)... 

Alkylethers (269), R2 = alkyl, are obtained by the action of phosphorus pentasulfide on alkyl esters of a-acylamino acids (64, 334, 711) by means of the GabriePs synthesis (Section II.4), while aryl ethers (269), = aryl,... 

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... 

The addition of a-(acylamino) esters to 3-aryl-2-propenoates, with sodium ethoxide in ethanol or sodium hydride in benzene as base, is a frequently ultilized procedure9-" A The initial Michael adducts cyclize to 3-aryl-5-oxo-2-pyrrolidinecarboxylic acids with modest to high trans diastereoselectivities 10°. 

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>. 

Compared with 3-alkyl-3-(acylamino)acrylic acid derivatives, much less success has been obtained in the asymmetric hydrogenation of 3-aryl-3-(acylamino)acrylic acid derivatives. An Et-FerroTANE-Rh catalyst has provided up to 99% ee for the hydrogenation of a series of (E)-3-aryl-3-(acylamino)acrylates.95 Since (E)-3-aryl-3-(acylamino)-acrylic acid derivatives are difficult to obtain in large scales compared to (Z)-3-aryl-3-(acylamino)acrylic acid... 

A striking feature of disperse dye development in recent decades has been the steady growth in bathochromic azo blue dyes to replace the tinctorially weaker and more costly anthraquinone blues. One approach is represented by heavily nuclei-substituted derivatives of N,N-disubstituted 4-aminoazobenzenes, in which electron donor groups (e.g. 2-acylamino-5-alkoxy) are introduced into the aniline coupler residue and acceptor groups (acetyl, cyano or nitro) into the 2,4,6-positions of the diazo component. A PPP-MO study of the mobility of substituent configurations in such systems demonstrated that coplanarity of the two aryl rings could only be maintained if at least one of the 2,6-substituents was cyano. Thus much commercial research effort was directed towards these more bathochromic o-cyano-substituted dyes. 

A-Alkyl- and A-aryl-a-acylamino acids with a mixture of acetic anhydride and perchloric acid form 1,3-oxazolonium perchlorates... 

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). 

More drastic hydrolysis conditions of unsaturated oxazolones 448 leads to further hydrolysis of the intermediate 2-acylamino-2-alkenoic acid 449 and produces the corresponding a-keto acids 450. For example, phenylpyruvic acid " and other aryl(heteroaryl)pyruvic acids of biological interest have been obtained in this manner (Scheme 7.148). 

A -Acylamino aromatic ketones 790 can be prepared by arylation of saturated oxazolones in the presence of Lewis acids. Cyclodehydration of 790 leads to 2,5-diaryloxazoles 791. For example, saturated 5(4//)-oxazolones 789 from 7/-benzoyl-alanine or A-benzoylvaline undergo Friedel-Crafts arylation to afford substituted A-benzoylphenacylamines 790. In the presence of POCI3, 790 cyclizes to produce 5-aryl-2-phenyloxazoles 791 (Scheme 7.241). ... 

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