67811-38-5Relevant academic research and scientific papers
Formation and Reactions of the Cyclic Tautomers of Tryptophans and Tryptamines. VII. Hydroxylation of Tryptophans and Tryptamines
Taniguchi, Mikio,Anjiki, Tomiko,Nakagawa, Masako,Hino, Tohru
, p. 2544 - 2554 (2007/10/02)
The 5-hydroxytryptophan derivative 12 was prepared in 60percent yield from the tryptophan derivative 8 by selective oxidation of the cyclic tautomer 9 with Fremy's salt or Pb(OAc)4-CF3COOH to the p-quinoneimine 10, followed by reduction and ring-opening.By analogous oxidation, serotonin was prepared from tryptamine.On the other hand, the oxidation of the Na-acetyl-cyclic tautomers (16 and 22) with Pb(OAc)4-CF3COOH followed by methylation gave the 5- and 6-methoxy derivatives (17, 18, 23, and 24) in 20-40percent yields.These compounds were readily converted to the 5- and 6-methoxytryptophan derivatives (20, 21) by acid treatment.These methods are the first practical hydroxylation procedures to be reported for tryptophans.Keywords: 5-hydroxytryptophan; methoxytryptophan; cyclic tautomer; tryptophan; oxidation; hydroxylation; lead tetraacetate; Fremy's salt.
Cyclic Tautomers of Tryptophans and Tryptamines. VI. Preparation of Na-Alkyl-, 5-Chloro-, and 5-Nitrotryptophan Derivatives
Taniguchi, Mikio,Gonsho, Akinori,Nakagawa, Masako,Hino, Tohru
, p. 1856 - 1865 (2007/10/02)
Selective Na-alkylation , 5-chlorination, 5-bromination, and 5-nitration of tryptophan derivatives were achieved.The alkylation of the cyclic tautomer 2 of Nb-methoxycarbonyl-DL-tryptophan methyl ester (1) with alkyl halides in acetone-K2CO3 gave the Na-alkyl derivatives (3a and 4) in excellent yields.The chlorination of the cyclic tautomer 3b with NCS-AcOH gave the 5-chloro derivative (5b) in 89percent yield, and this was readily converted to the 5-chlorotryptophan derivatives (7a, 7b, 9).The similar chlorination of 12 gave the 5-chloro derivatives (13a, 15a) and the 3a-chloropyrroloindole derivative (17).On the other hand the bromination of 12 with NBS-AcOH gave the 5-bromo derivative (13b) in good yield, and this was readily converted to 15d and further to 15c.The nitration of 3b and 12 with fuming nitric acid also gave the 5-nitro derivatives (5c, 7c, 13c, 15e) in excellent yields.Keywords --- tryptophan derivatives; cyclic tautomer of Nb-acyltryptophans; chlorination; bromination; nitration; N-alkylation; 5-substituted tryptophan derivatives; N-chlorosuccinimide; N-bromosuccinimide
CYCLIC TAUTOMERS OF TRYPTOPHANS AND TRYPTAMINES-4; SYNTHESIS OF CYCLIC TAUTOMERS OF TRYPTOPHANS AND TRYPTAMINES
Taniguchi, Mikio,Hino, Tohru
, p. 1487 - 1494 (2007/10/02)
Nb-Methoxycarbonyltryptophan methyl ester (DL- and L-13) was cyclized to the corresponding trans cyclic tautomer (14) in excellent yield in various acids such as 85percent phosphoric acid or trifluoroacetic acid.The cis cyclic tautomer (15) was formed as the less stable and kinetically controlled product and converted to the more stable trans isomer (14) under the reaction condition.The trans isomer (14) was reverted to 13 on treatment with 10percent sulfuric acid in methanol.Other tryptophan and tryptamine derivatives (6 and 19a) also cyclized to the corresponding cyclic tautomers in similar acidic media.
