A New<i>N</i>-Spiro C<sub>2</sub>-Symmetric Chiral Quaternary Ammonium Bromide Consisting of 4,6-Disubstituted Biphenyl Subunit as an Efficient Chiral Phase-Transfer Catalyst
作者:Keiji Maruoka、Takashi Ooi、Yasushi Kubota
DOI:10.1055/s-2003-41478
日期:——
A new N-spiro chiral quaternary ammonium bromide has been designed and assembled from opticallyactive 4,6-disubstituted biphenyl subunits. Its utility as an efficient chiralphase-transfercatalyst has been clearly demonstrated by application to the highly enantioselectivealkylation of tert-butyl glycinate benzophenone Schiff base.
Design of new, chiral phase-transfer catalysts for practical, catalytic asymmetric synthesis
作者:Keiji Maruoka
DOI:10.1016/s0022-1139(01)00472-9
日期:2001.11
Structurally rigid, chiral spiro ammonium salts of type 1 derived from commercially available (S)-binaphthol have been designed as a new C2-symmetricchiralphase-transfercatalyst and successfully applied to the highly efficient, catalytic enantioselective alkylation of tert-butyl glycinate Schiff base under mild phase-transfer conditions to furnish α-alkyl-α-amino acids and α,α-dialkyl-α-amino acids with excellent
Synthesis and application of dimeric Cinchona alkaloid phase-transfer catalysts: α,α′-bis[O(9)-allylcinchonidinium]-o, m, or p-xylene dibromide
作者:Sang-sup Jew、Byeong-Seon Jeong、Mi-Sook Yoo、Hoon Huh、Hyeung-geun Park
DOI:10.1039/b102584h
日期:——
A dimeric Cinchona alkaloid ammonium salt,
α,αâ²-bis[O(9)-allylcinchonidinium]-m-x
ylene dibromide 4, has been developed as a new efficient phase-transfer
catalyst; the catalytic enantioselective alkylation of
N-(diphenylmethylene)glycine tert-butyl ester using 4
provided 7 in a high enantiomeric excess (90â99% ee).
practical chiral phase-transfercatalysts (PTCs). Presented are the details on the development of the dimeric PTCs for the synthesis of optically active α-aminoacid derivatives and the optimization of the reaction variables suitable for the dimeric PTCs. The 1,3-phenyl- and the 2,7-naphthyl-linked dimeric PTCs showed excellent catalytic capability on the reactivity and enantioselectivity in the catalytic
Two new cinchona phasetransfercatalysts are prepared from dihydrocinchonidine using 13-picenylmethyl bromide and 1-pyrenylmethyl bromide, respectively. A total contrast in catalytic efficiency is observed during the asymmetric alkylation of glycinate esters; with one catalyst, the reaction is either incomplete or the enantioselectivity is very poor (15% ee) while the other catalyst afforded high