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The Syntheses of new Camphorsulfonylated Ligands Derived from 2‐Amino‐2′‐Hydroxy‐1,1′‐Binaphthyl and Their Enantioselectivities in the Addition of Dialkylzinc Reagents to Aldehydes
Author(s) -
Bian Guangling,
Huang Huayin,
Zong Hua,
Song Ling
Publication year - 2012
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.22078
Subject(s) - chemistry , enantioselective synthesis , bimetallic strip , catalysis , reagent , ligand (biochemistry) , nucleophile , chiral ligand , titanium , titration , combinatorial chemistry , organic chemistry , stereochemistry , medicinal chemistry , biochemistry , receptor
A series of new camphorsulfonylated ligands derived from chiral 2‐amino‐2′‐hydroxy‐1,1′‐binaphthyl (NOBIN) and (+)‐camphorsulfonic acid were synthesized by a short and simple synthetic sequence, and their enantioselective catalytic activities were assessed in the nucleophilic addition reaction of dialkylzinc reagents to aldehydes in the presence of titanium tetraisopropoxide. The most efficient ligand, N ‐hydroxycamphorsulfonylated ( S )‐NOBIN, gave ( S )‐addition products with good yields and up to 87% of ee value. The 1 H nuclear magnetic resonance (NMR) and 13 C NMR results of the titanium titration experiments on this ligand indicate that the most likely catalytic reactive species involved in this catalytic asymmetric addition is a bimetallic titanium complex. A possible catalytic reaction mechanism is proposed. Chirality 24:825–832, 2012. © 2012 Wiley Periodicals, Inc.