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Phase-transfer catalysis is one of the most useful methodologies for practical syntheses given its operational simplicity and mild reaction conditions that enable its application in industrial processes. Cinchona alkaloids have been a popular, natural source of practical organocatalysts due largely to their excellent commercial availability and low cost. Since the first Cinchona alkaloid-derived phase-transfer catalysts was disclosed in 1981, diverse generations of Cinchona-derived phase-transfe

[structure: see text] Various N-benzylcinchonidinium salts were prepared to study electronic factors in the catalytic enantioselective phase-transfer alkylation of glycine anion equivalent. An ortho-fluoro substituent on the benzyl group in the quaternary ammonium salt dramatically increased the enantioselectivity in the alkylation. O(9)-Allyl-N-2',3',4'-trifluorobenzylhydrocinchonidinium bromide (27), which gave the highest enantioselectivity of the catalysts studied, was used to prepare 12 alp

A dimeric Cinchona alkaloid ammonium salt, α,α′-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 (90–99% ee).

A novel enantioselective synthetic method for the construction of a quaternary carbon center from malonates via phase-transfer catalytic (PTC) alkylation has been developed. The asymmetric α-alkylation of diphenylmethyl tert-butyl α-alkylmalonates with alkylating agents under phase-transfer catalysis conditions (aq 50% KOH, toluene, 0 °C) in the presence of (S,S)-3,4,5-trifluorophenyl-NAS bromide (8) as PTC catalyst afforded the corresponding α,α-dialkylmalonates in high chemical (up to 99%) and

Potenzielle Katalysatoren für industrielle Syntheseprozesse zur Herstellung natürlicher und nichtnatürlicher chiraler α-Aminosäuren sind die dimeren, auf Naphthalin basierenden Cinchona-Alkaloide 1 aufgrund der milden Reaktionsbedingungen und hohen katalytischen Effizienz (hohe Ausbeuten und ee-Werte). Sie fungieren als Phasentransferkatalysatoren bei der Alkylierung eines Glycin-Derivats. Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2

A new enantioselective synthetic method of (-)-paroxetine is reported. (-)-Paroxetine could be obtained in 15 steps (95% ee and 9.1% overall yield) from N,N-bis(p-methoxyphenyl)malonamide tert-butyl ester via the enantioselective phase-transfer catalytic alkylation and the diastereoselective Michael addition as the key steps.

A new efficient and concise enantioselective synthetic method for (-)-horsfiline is reported. (-)-Horsfiline could be obtained from diphenylmethyl tert-butyl malonate in 9 steps (32%,>99% ee) by using the enantioselective phase-transfer catalytic allylation (91% ee) as the key step. This approach can be applied as a practical route for the large-scale synthesis of spirooxindole natural products, which enables a systematic investigation of their biological activity to be performed.

An efficient enantioselective synthetic method for (S)-alpha-alkyl-alpha,beta-diaminopropionic acid is reported. The asymmetric phase-transfer catalytic alkylation of N(1)-Boc-2-phenyl-2-imidazoline-4-carboxylic acid tert -butyl ester in the presence of chiral quaternary ammonium catalyst gave the corresponding alkylated products (93-98% ee) which could be transformed to enantioenriched alpha-alkyl-alpha,beta-diaminopropionic acids.