駿太郎 又賀

Synthesis of 2-Aminomethyl-5-tert-butylphenols

Mannich-type aminomethylation of m-ten-butylphenol (1) with a variety of secondary amines and formalin was carried out in ethanol at 70-80°C for 2 h. The reaction with amines such as pyrrolidine, piperidine, N-methylpiperazine, and N-benzylpiperazine gave the expected products, 2-pyrrolidinomethyl(2b), 2-piperidinomethyl(2d), 2-(N-methylpiperazino)methyl(2e), and 2-(N-benzylpiperazino)-methyl-5-te11-butylphenol (2 f) in high yields. In the reaction with piperazine, the desired compound, 2-(piperazinomethyl)-5-ten-butylphenol (2g) was not fonned and N,N-bis(2-hy<toxy4-tert-butylbenzyl)piperazine (3) and bis[N,N-di (2-hy<toxy-4-ten-butylbenzyl)]piperazinomethane (4) were produced in 52% and 38% yields, respectively. 2-(Dimethylamino)methyl-5-te11-butylphenol (2a) was obtained, albeit in a poor yield, when aqueous 10 % potassium hydroxide solution was a.tIed to the reaction mixture with dimethylammonium chloride to generate the free amine. Addition ofthe base was effective in the Mannich conoonsation with morpholine, giving the OOsired 2(morpholino)methyl-5-ten-butylphenol (2c) in a moderate yield Without the base, the reaction did not occur.

Ring-opening Reaction of 6,8-Di-t-butyl-1,2,3,4-tetrahydro-9aH-pyrido [2,1-b] benzoxazole

Treatment of 6, 8-di-t-butyl-1, 2, 3, 4-tetrahydro-9aH-pyrido [2, 1-b]benzoxazole (3a) with conc, hydrochloric acid gave 2,4-di-t-butyl-6-piperidino-phenol (4) and 2,4-di-t-butyl-6-(2-oxopiperidino)phenol (5) in 26 and 25% yields. Reaction of 3a with acetic anhydride afforded 2,4-di-t-butyl-6-[1-(1, 2, 3, 4-tetrahydro-5-acetylpyridyl)] phenyl acetate (6) and 6, 8-di-t-butyl-1-acetyl-2, 3, 4, 4a-tetrahydropyrido [2, 1-b] benzoxazole (7) in 41 and 25% yields. Hofmann degradation of the quarternary salts of 3a with methyl and ethyl iodide gave the expected ring-opend [1, 4] oxazonines, 10a and 10b, in 43 and 10% yields, respectively.