3- Methyl thiophene

Stufe (H3C)3C -OH/ 1,4-Dioxan, Riickfl. h 2. Stufe HCl/H C-COOH 0r, bis zur Homogenitat dann Amin HC1 mit Ether fallen [2-tert.-Butoxyearbonylamino-5-methyl-thiophen - ] 2-Amino-S-methyl-thiophen [92] 82 6 6... 

Methyl-substituted thiophenes are also capable of reaction with benzalaniline, provided that the 5-position carries a carbo- or heterocyclic aromatic group, as, for example, 2-(benzoxazol-2-yl)-5-methyl-thiophene (109), which yields the styryl derivative 110.11 The isomeric compound 111 may be obtained analogously from 2-(/ -tolyl)benzox-azole and Schiff s base from 2-formylthiophene and p-chloroaniline. 

Model reactions showed that 2-dodecyl-5-methyl thiophene, benzo[b]thiophene, 2-n-butyl benzo[b]thiophene and dibenzothiophene were unaffected by these reaction conditions after a 4-hour reflux. For the LiAlH4 reduction step the solvent dioxane (b.p. 100°C) is preferred to either diethyl ether or tetrahydrofuran since preferential reduction of certain sulfides in the latter solvents has been observed (2). The results of the sulfide analyses for several petroleums from Alberta are summarized in Table I. 

Fig. 6. "B-NMR data for 2-diethylboryl-5-methyl thiophene (a) and its pentacarbonyl-chromium complex (b). In the latter, donor-acceptor relationship between boron and the carbonyl group is postulated to account for its higher field nB shift (c).

Methyl-thiophen.caTbons4are-(2) 18, 295. CarbonR ure CjHjOjS, vielleicht 2.3-Carb>... 

Where, R = 2-Fluorophenyl, 4-methox5q)henyl, 3-hydroxyphenyl, furan-2-yl-, ethyl, 4-(dimethylamino)phenyl, 5-methyl-thiophen-2yl. 

---