ethyl 2-oxo-2-(5-phenylmethoxy-1H-indol-3-yl)acetate → 6-Benzyloxy-1,1-dimethyl-1,3,4,9-tetrahydropyrano[3,4-b]indole

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Reaction Steps

5-Benzyloxy-3-tryptophol (II; R2, R3, R4 and R5 = H, R6 = 5-benzyloxy and X1 = OH), m.p. 93° - 95° C., is prepared by lithium aluminum hydride reduction of ethyl 5-benzyloxy-3-indoleglyoxalate (British Patent 778,823) according to the procedure of Example 309. Subsequent treatment of 5-benzyloxy-3-tryptophol with the ketone, acetone, according to the procedure of Example 785 affords 6-benzyloxy-1,1-dimethyl-1,3,4,9-tetrahydropyrano[3,4-b]indole (VII; R1M CH3), nmr (CDCl3) δ1.53 (6H), 2.73 (t, 2H), 4.03 (t, 2H), 5.10 (2H), 6.67 - 7.83 (9H). The latter compound is then N-alkylated with the organic halide, dimethylaminoethyll chloride, according to the procedure of Example 838 to afford 6-benzyloxy-1,1-dimethyl-9-[2-(dimethylamino)ethyl]-1,3,4,9-tetrahydropyrano[3,4-b]indole, which on treatment with hydrochloric acid gives the corresponding hydrochloric acid addition salt thereof, m.p. 209° C.

Provenance & Evidence