691885-26-4Relevant academic research and scientific papers
General synthesis of unnatural 4-, 5-, 6-, and 7-bromo-D-tryptophans by means of a regioselective indole alkylation
Bartoccini, Francesca,Fanini, Fabiola,Retini, Michele,Piersanti, Giovanni
, (2020/04/21)
A general two-step approach to enantiopure bromotryptophans from unprotected bromoindoles has been developed. Indole nucleophiles prepared with MeMgCl in the presence of CuCl reacted with cyclic sulfamidates derived from enantiopure D-serine to form 4-, 5-, 6-, or 7-bromo-D-tryptophan and some other halogenated tryptophans in moderate yields but with complete regioselectivity. The bromotryptophan derivatives were deprotected using mild conditions.
Total synthesis without protection: Three-step synthesis of optically active clavicipitic acids by a biomimetic route
Yokoyama, Yuusaku,Hikawa, Hidemasa,Mitsuhashi, Masaharu,Uyama, Aki,Hiroki, Yasuhiro,Murakami, Yasuoki
, p. 1244 - 1253 (2007/10/03)
A three-step synthesis of a mixture of optically active cis- and frans-clavicipitic acids 6, which are ergot alkaloids, was achieved, starting from 4-bromoindole (7) and dl-serine (dl-2). This short synthesis was made possible by omitting the protection and deprotection steps from the synthetic route. The key step was the spontaneous cyclization of 4-vinyltryptophan (10) formed from the Heck reaction of 4-bromotryptophan (8) with 2-methyl-3-buten-2- ol (9) in aqueous media. During this investigation, we also found that the palladium-catalyzed reaction of 8 with 9 showed an interesting pH dependence; under strongly basic conditions, the Heck reaction occurred to give a C 4-vinylated product 10, whereas an N-allylated product 19b was formed under neutral or weakly basic conditions. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
