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Phosphinooxazolines Derived from 3‐Amino‐1,2‐diols: Highly Efficient Modular P‐N Ligands
Author(s) -
Popa Dana,
Puigjaner Cristina,
Gómez Montserrat,
BenetBuchholz Jordi,
VidalFerran Anton,
Pericàs Miquel A.
Publication year - 2007
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.200600599
Subject(s) - chemistry , tsuji–trost reaction , enantiopure drug , substituent , alkylation , moiety , allylic rearrangement , enantioselective synthesis , oxazoline , stereochemistry , aryl , chirality (physics) , catalysis , medicinal chemistry , organic chemistry , alkyl , nambu–jona lasinio model , chiral symmetry breaking , physics , quantum mechanics , quark
A family of chiral phosphinooxazolines ( 12a–e) derived from modular, enantiopure β‐amino alcohols has been prepared, and their palladium complexes have been used as chiral mediators in the asymmetric allylic alkylation reaction. The oxazoline moiety in 12 contains a C‐4 aryl and a C‐5 alkoxymethyl substituent that can be independently optimized for high catalytic activity and enantioselectivity. A methoxymethyl substituent at C‐5 has been found to provide the best results in terms of enantioselectivity and activity in the alkylation of a diverse family of allylic substrates under both thermal and microwave‐assisted activation. The palladium‐phosphinooxazoline complexes described in this work are remarkably robust, as the enantioselectivity recorded in the asymmetric allylic alkylation remains essentially unchanged in the temperature range between 20 and 130 °C. An unprecedented reversal in enantioselectivity has been observed between 1,3‐diphenylallyl and 1,3‐dimethylallyl alkylation substrates, and the origin of this behavior has been explained by means of ONIOM QM/MM calculations.