TY - JOUR
T1 - Catalytic enantioselective chlorination and bromination of β-keto esters
AU - Hintermann, Lukas
AU - Togni, Antonio
PY - 2000
Y1 - 2000
N2 - The Ti(TADDOLato) complexes dichloro[(4R,5R)-2,2-dimethyl-α,α,α',α'-tetraphenyl-1,3-dioxolane-4,5-dim ethanolato(2 -)-O,O']titanium ((R)-1a) and dichloro[(4R,5R)-2,2-dimethyl-α,α,α',α'-tetra(naphthalen-1-yl)-1,3-dioxol ane-4,5-dimethanolato(2-)-O,O']titanium ((R)-1b) are efficient catalysts for the electrophilic enantioselective chlorination and bromination of β-keto esters with N-chlorosuccinimide (NCS) and N-bromosuccinimide (NBS), respectively. With 5 mol-% of catalyst at room temperature an enantioselectivity of up to 88% ee could be obtained for the chlorination reaction. Under comparable conditions, bromination reactions are slower and less stereoselective.
AB - The Ti(TADDOLato) complexes dichloro[(4R,5R)-2,2-dimethyl-α,α,α',α'-tetraphenyl-1,3-dioxolane-4,5-dim ethanolato(2 -)-O,O']titanium ((R)-1a) and dichloro[(4R,5R)-2,2-dimethyl-α,α,α',α'-tetra(naphthalen-1-yl)-1,3-dioxol ane-4,5-dimethanolato(2-)-O,O']titanium ((R)-1b) are efficient catalysts for the electrophilic enantioselective chlorination and bromination of β-keto esters with N-chlorosuccinimide (NCS) and N-bromosuccinimide (NBS), respectively. With 5 mol-% of catalyst at room temperature an enantioselectivity of up to 88% ee could be obtained for the chlorination reaction. Under comparable conditions, bromination reactions are slower and less stereoselective.
UR - http://www.scopus.com/inward/record.url?scp=0033790769&partnerID=8YFLogxK
U2 - 10.1002/1522-2675(20000906)83:9<2425::AID-HLCA2425>3.0.CO;2-V
DO - 10.1002/1522-2675(20000906)83:9<2425::AID-HLCA2425>3.0.CO;2-V
M3 - Article
AN - SCOPUS:0033790769
SN - 0018-019X
VL - 83
SP - 2425
EP - 2435
JO - Helvetica Chimica Acta
JF - Helvetica Chimica Acta
IS - 9
ER -