Catalytic Hydrogenation of 9 to 14. A 14-mg sample of platinum oxide in 1 mL of ethyl acetate was prehydrogenated, and the slurry was cooled to -20 °C. A solution of 9 (105 mg, 0.43 mmol) in 4 mL of ethyl acetate was introduced, and hydrogenation was resumed until ca. 9 mL of hydrogen was taken up. The mixture was filtered through Celite, and the fíltrate was evaporated to give 103 mg (977c) of 14 whose spectra were superimposable upon those of the substance prepared above.Diimide Reduction of 14. Following the standard procedure, 1.5 g (6.12 mmol) of 14 in 45 mL of ethanol was reduced with 4.3 g (134 mmol) of hydrazine and 6.2 mL of hydrogen peroxide. Workup gave 235 mg (15.6%) of 11, a colorless solid: mp 157-158 °C (from ethyl acetate-hexane); NMR (CDClg) 4.45 (pseudo s, 2 ), 3.03 (s, 3 ), 2.52-137 (series of m, 12 H); 13C NMR (CDClg) 158.2 (s), 60.4 (d), 47.8 (d), 42.3 (t), 39.4 (d), 35.7 (t), 25.6 (q), 24.3 (t) ppm; mass spectrum, m/e caled 247.1321, obsd 247.1327.
Allylic alcohols, amines, tetrahydropyranyl ethers, IV-allylphthalimide, and tetraallyl silicate have been reacted with various vinylic bromides and, in some cases, bromobenzene by using a palladium catalyst with an amine as an acid acceptor. Of the allylic alcohols, methallyl alcohol was the most useful synthetically. It produced 4-enals in modest yields in many examples without formation of the regioisomers which are a problem in other cases. Secondary allylic alcohols reacted regioselectively to form mixtures of 4-enals and amino alcohols. Some nonallylic alcohols gave good yields of amino alcohols, also. Allylic tertiary amines reacted more selectively in some instances than allylic alcohols, producing 4-enals after hydrolysis of the enamine products. The allylic tetrahydropyranyl ethers, in general, formed mixtures of dienyl ethers and amino alkenyl ethers. The JV-allylphthalimide-vinylic bromide reactions were the most selective we found. The products were 7V-(2,4-dienyl) phthalimides, formed in fair to good yields. The reactions of tetraallyl silicate were of limited value. The reaction was selective with bromobenzene, forming after hydrolysis only cinnamyl alcohol, but it was not selective with vinylic halides, and conversions were always low due to facile reduction and inactivation of the catalyst under the reaction conditions.
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