A series of derivatives of 2,3‐dimethylquinoxaline‐6‐carboxaldehyde 1,4‐dioxide was prepared. Derivatives prepared included nitrones, semicarbazide, and aminooxazolidinone.

No abstract

Notes described above for 7a ( = 2, 4) except that the vols of H20 and DMF were increased 2.5-3 times.IV. S,S'-3,8-Diazaundecamethylenebis (dihydrogen phosphorothioate) (8a) was prepared by the procedure used for the prepn of 7a ( = 2,4).V. N,N'-(trans-l, 4-Cyclohexylene )bis(Y'-(czs-l,4-Cyclohexyienedimethylene)bis(S-2-aminoethyl lithium hydrogen phosphorothioate) (13a) was prepd in the manner described for 12a (re = 1). 2,2'-[

The methylnitrone of 3-methyl-1,4-dioxidoquinoxaline-2-carboxaldehyde (1) has been exceptional antibacterial activity in vivo. Derivatives of 3-hydroxymethyl-1,4-dioxidoquinoxaline-2-carboxaldehyde and 3-acetoxymethyl-1,4-dioxidoquinoxaline-2-carboxaldehyde were prepared. Several of these compounds were found to be antibacterial agents of the same order of activity as I.

269Ethyl acetoacetate reacted with 3-bromo-1,l ,l-trifluoro-2-propanone in the presence of base to give 3-carbethoxy-4,5-dihydro-4-hydroxy-2-methyl-4-trifluoromethylfuran (I). Acid catalyzed dehydration of I gave the corresponding furan (111). Saponification of 111 gave 2-methyl-4trifluoromethyl-3-furoic acid which was decarboxylated to yield 2-methyl-4-trifluoromethylfuran (V) for which a structure proof is presented. Conversion of the methyl groups of 111 and V to formyl groups is described.In a previous paper (1) the preparation of some 5-trifluoromethylfuran derivatives was described. This report discusses the synthesis of several 4-trifluoromethyIfurans.Addition of one equivalent of sodium ethoxide to a benzene solution of ethyl acetoacetate and 3-bromo-1,I , Itrifluoro-Z-propanone gave a product (I) which was readily dehydrated under acidic conditions to give an ester, 111. On saponification and decarboxylation of 111 a compound (V) was obtained which analyzed as a methyltrifluoromethylfuran. If the initial reaction to produce I was similar to previously reported ( 1,2) condensations of a-halopropanones with ethyl acetoacetate using strong base, the product, V, should have been 2-methyl-5-trifluoromethylfuran. However, comparison of the infrared and NMK spectra of V with spectra obtained from an authentic sample of 2-methyl-5-trifluoromethylfuran ( I ) indicated that the compounds were not the same. Examination of the NMR of V showed, in addition to the signal from the methyl group at 6 2.24, one-proton singlets at 6 6.12 and 6 7.55, a pattern which suggested that V was a 2,4-disiibstituted furan. This type of product is typical of those isolated from the Feist-Benary synthesis (3) and other closely related condensations in which a-haloketoesters are condensed with 0-ketoesters (4). In order to definitely establish the structure of V it was condensed with diethyl acetylenedicarboxylate to give the Diels-Alder adduct, VI. The adduct was hydrogenated over palladium on charcoal and then heated at 180", effecting a retrograde Diels-Alder reaction. Comparison of the product with an authentic sample of diethyl 2-methylfuran-3,4dicarboxylate (5) showed them to be identical. The formation of this compound established the structure of V as 2-methyl-4-trifluoromethylfuran.Comparison of the NMR of V with the NMR of the acid (IV) from which it was formed showed that when the carboxyl group was present the signal due to the upfield proton on the three position of the furan ring disappeared.This observation established the structure of IV and its ethyl ester (111) as 2-methyl-4-trifluoromethyl-3-furoic acid and ethyl Z-methyl-4-trifluorornethyl-3-furoate, respectively.These findings left only the structure of the initial condensation product, I, to be established. Dunlop and Hurd (4) were the first to question the postulate that CHART I