cas 480427-57-4, O,O'-DIALLYL-N,N'-(2,7-NAPHTHALENEDIYLDIMETHYL)BIS(HYDROCINCHONIDINIUM)DIBROMIDE

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Phase-transfer catalyzed asymmetric arylacetate alkylation
Phenethyl arylacetates are alkylated under phase-transfer conditions with cinchona catalysts with alkyl halides in high yield with excellent enantioselectivity (84-99% ee) following recrystallization. Cinchonidine (CD) derived catalyst gave the (R)-product and cinchonine (CN) catalyst produced the (S)-product. The phenethyl (PE) ester group is removed, using ammonium formate and catalytic Pd/C, to give alkylated carboxylic acid products in high selectivity. The utility of the approach is demonstrated by a direct synthesis of (S)-naproxen.
Andrus, Merritt B.,Harper, Kaid C.,Christiansen, Michael A.,Binkley, Meisha A.
supporting information; experimental part
p. 4541 - 4544
(2009/12/03)

Synthesis of kurasoin B using phase-transfer-catalyzed acylimidazole alkylation
The hydroxy ketone natural product kurasoin B is synthesized using a phase-transfer-catalyzed alkylation reaction with benzyloxyacetyl imidazole. A biscinchonidinium dimethylnaphthalene catalyst allowed for high yield and near complete selectivity (99% ee
Christiansen, Michael A.,Butler, Aaron W.,Hill, Amanda R.,Andrus, Merritt B.
body text
p. 653 - 657
(2009/08/07)

Polymeric chiral phase-transfer catalysts derived from cinchona alkaloids for enantioselective synthesis of α-amino acids
A series of dimeric/trimeric chiral quaternary ammonium salts derived from cinchona alkaloids were designed as efficient and practical chiral phase-transfer catalysts (PTCs). Presented are the details on the development of the dimeric PTCs for the synthesis of optically active α-amino acid 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 phase-transfer alkylation of N-(diphenylmethylene)glycine tert-butyl ester (1). A variety of α-amino acid derivatives were obtained with high enantiopurities using the dimeric PTCs, especially the 2,7-naphthyl-dimer 41, in a very practical manner.
Lee, Jeong-Hee,Yoo, Mi-Sook,Jung, Ji-Hee,Jew, Sang-sup,Park, Hyeung-geun,Jeong, Byeong-Seon
p. 7906 - 7915
(2008/02/09)

Phase-transfer-catalyzed asymmetric acylimidazole alkylation
(Chemical Equation Presented) 2-Acylimidazoles are alkylated under phase-transfer conditions with cinchonidinium catalysts at -40°C with allyl and benzyl electrophiles in high yield with excellent enantioselectivity (79 to >99% ee). The acylimidazole substrates are made in three steps from bromoacetic acid via the N-acylmorpholine adduct. The catalyst is made in high purity allowing for S-product formation (6-20 h) under mild conditions, consistent with an ion-pair mechanism. The products are readily converted to useful ester products using methyltriflate and sodium methoxide, via a dimethylacylimidazolium intermediate without racemization. The process is efficient, direct, and amenable to other electrophiles and transformations that proceed through an enolate intermediate.
Andrus, Merritt B.,Christiansen, Michael A.,Hicken, Erik J.,Gainer, Morgan J.,Bedke, D. Karl,Harper, Kaid C.,Mikkelson, Shawn R.,Dodson, Daniel S.,Harris, David T.
p. 4865 - 4868
(2008/03/14)