[C:1]([CH2:5][C:6]1[N:7]2[CH:13]=[C:12]([C:14]3[CH:19]=[CH:18][CH:17]=[CH:16][CH:15]=3)[CH:11]=[C:8]2[S:9][CH:10]=1)([O:3][CH3:4])=[O:2].CN(C)[CH:22]=[O:23].P(Cl)(Cl)(Cl)=O.[OH-].[Na+]>O.C(N(CC)CC)C>[C:1]([CH2:5][C:6]1[N:7]2[C:13]([CH:22]=[O:23])=[C:12]([C:14]3[CH:19]=[CH:18][CH:17]=[CH:16][CH:15]=3)[CH:11]=[C:8]2[S:9][CH:10]=1)([O:3][CH3:4])=[O:2]
A solution of 200 mg. of 3-carbomethoxymethyl-6-phenylpyrrolo[2,1-b] thiazole in 2 ml. of dimethylformamide is cooled to -40°, and 500 mg of a 1:2 mixture of phosphorous oxychloride:dimethylformamide is added. The temperature of the reaction is maintained at -40° C. for 30 minutes, then 2 ml of triethylamine are added and the mixture allowed to warm to room temperature. After 2 hours, 2 ml of 10% sodium hydroxide solution are added; the reaction mixture is diluted with water and extracted four times with ether. The combined ether extracts are diluted with hexane and washed with water. After drying and evaporation, the residue is chromatographed on 10 g of silica gel. Elution with chloroform initially gives 3-carbomethoxy-5-phenylthiacycl[2.2.2]azine as a brilliant yellow material, intensely fluorescent under long wavelength ultra-violet light, which may be crystallized from hexane, m.p. 118°-120°. Continued elution with chloroform affords 3-carbomethoxymethyl-5-formyl-6-phenylpyrrolo[2,1-b] thiazole, δ 3.70(3H), 4.42(2H), 6.40(1H), 6.61(1H), 0.93(1H) ppm. 150 Mg. of this aldehyde is refluxed in 100 ml of tetrahydrofuran with 0.5 ml. of triethylamine, 5 mg. of p-toluenesulfonic acid, and 20 ml of pentamethylsilazane to give an additional amount of 3-carbomethoxy-5-phenylthiacyl[2.2.2] azine.
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