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New route to enantiopure MαNP acid, a powerful resolution and chiral 1 H NMR anisotropy reagent
Author(s) -
Naito Junpei,
Taji Hiromi,
Sekiguchi Satoshi,
Watanabe Miwa,
Kuwahara Shunsuke,
Watanabe Masataka,
Harada Nobuyuki
Publication year - 2007
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.20385
Subject(s) - enantiopure drug , chemistry , diastereomer , amide , chirality (physics) , oxazoline , reagent , absolute configuration , moiety , amine gas treating , organic chemistry , stereochemistry , catalysis , enantioselective synthesis , chiral symmetry , physics , quantum mechanics , quark , nambu–jona lasinio model
MαNP acid (±)‐ 1 , 2‐methoxy‐2‐(1‐naphthyl)propionic acid, was enantioresolved by the use of phenylalaninol ( S )‐(−)‐ 4 ; a diastereomeric mixture of amides formed from acid (±)‐ 1 and amine ( S )‐(−)‐ 4 was easily separated by fractional recrystallization and/or HPLC on silica gel, yielding amides ( R;S )‐(−)‐ 5a and ( S;S )‐(+)‐ 5b . Their absolute configurations were determined by X‐ray crystallography by reference to the S configuration of the phenylalaninol moiety. Amide ( R;S )‐(−)‐ 5a was converted to oxazoline ( R;S )‐(+)‐ 8a , from which enantiopure MαNP acid ( R )‐(−)‐ 1 was recovered. In a similar way, enantiopure MαNP acid ( S )‐(+)‐ 1 was obtained from amide ( S;S )‐(+)‐ 5b . These reactions provide a new route for the large‐scale preparation of enantiopure MαNP acid, a powerful chiral reagent for the enantioresolution of alcohols and simultaneous determination of their absolute configurations by 1 H NMR anisotropy. Chirality, 2007. © 2007 Wiley‐Liss, Inc.