Ketones 4-alkoxy-5 -oxazolones

Two different methods have also been described for the synthesis of 4-alkoxy-5(2//)-oxazolones 50. In the first case, 4-(phenylthio)-5(277)-oxazolones 48 are oxidized to the 4-phenylsulfinyl derivatives that react with the alcohol present in the reaction medium to afford the corresponding 4-alkoxy derivatives. Alternatively, 4-alkoxy-5(2//)-oxazolones 50 have been obtained by condensation of iminooxalates and ketones in acidic medium. (Scheme 7.12 Table 7.7, Fig. 7.8 Table 7.8, Fig. 7.9). 

TABLE 7.8. SYNTHESIS OE 4-ALKOXY-5(2H)-OXAZOLONES FROM IMINOOXALATES AND KETONES OR ALDEHYDES ... 

Alkoxy-5(2i/)-oxazolones are available from ethyl cyanoformate via a simple albeit poor yielding route <89HCA825>. Imino esters (173), formed from the cyanoformate and an alcohol, are reacted with a ketone or aldehyde in the presence of BF3 etherate to give the oxazolone and a triazine triester (174) as the main product (Scheme 83). In a related synthesis, tosyloxyiminoacetates... 

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See also in sourсe #XX -- [ , ]

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