Online article for Non-subscribers

Pay per view

Heterocycles has a pay-per-view service for Non-subscribers.
You will be able to directly purchase the full text article through PayPal.
Your purchased Paper can be downloaded after the payment is completed.
An e-mail will be sent the URL to download the paper.
If you have any questions, please contact:

Price: ¥ 4,400 (Yen only)
Period: This Article can be accessed for 7 days.

Note | Regular issue | Vol 65, No. 6, 2005, pp.1455-1459
Published online, 24th March, 2005
DOI: 10.3987/COM-05-10380
An Improved Synthesis of Optically Pure (R)-4-Bromo-N-methyl-1-tosyltryptophan Derivative, a Key Intermediate in the Synthesis of Ergot Alkaloids

Yuusaku Yokoyama,* Ryoko Hara, Nahoko Kato, Yasuoki Murakami, and Hiroaki Okuno

*School of Pharmaceutical Sciences, Toho University, 2-2-1, Miyama, Funabashi, Chiba 274-8510, Japan


Optically pure (R)-N-Boc- or (R)-Cbz-4-bromo-N-methyl-1-tosyltryptophan methyl ester (11a or b) was synthesized in 2 steps from (R)-N-acetyl-4-bromo-1-tosyltryptophan methyl ester (7) by simultaneous N-methylation and deacetylation using methyl trifluoromethanesulfonate (TfOMe) in the presence of 2,6-di-tert-butyl-4-methylpyridine (DTBMP).