Chemoselective O -methylation of N -acylated/sulfonylated tyrosine derivatives

Autor:	Mireille Attolini, Thierry Boxus, Jacqueline Marchand-Brynaert, Stéphane Biltresse
Rok vydání:	2002
Předmět:	Steric effects Chemistry Stereochemistry Phase (matter) Organic Chemistry Drug Discovery Diad Mitsunobu reaction Methylation Tyrosine Biochemistry
Zdroj:	Tetrahedron Letters. 43:1187-1188
ISSN:	0040-4039
DOI:	10.1016/s0040-4039(01)02349-8
Popis:	Methyl ethers (6a and 6b) of N-trifluoroacetyl- and N-(m-trifluoromethyl) phenylsulfonyl-6-nitro-tyrosine t-butyl ester were readily prepared by modified Mitsunobu reaction (DPPE. DIAD, MeOH). Williamson (Mel, K2CO3 or LiCO3 or NaOH under phase transfer) and classical Mitsunobu conditions (PPh3, DEAD, MeOH) gave O,N-dimethylated derivatives (7a and 7b) as side or main products. O- versus N-selectivity in tyrosine methylation reactions depends on both pK(a) values and steric factors. (C) 2002 Elsevier Science Ltd. All rights reserved.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::24e0ed1f71efc52f44b35f63c0006ef5 https://doi.org/10.1016/s0040-4039(01)02349-8 Zobrazit plný text záznamu Full Text from ScienceDirect