Phase-Transfer Catalysts

A phase-transfer catalyst enables the reaction in a heterogeneous system between general organic compounds soluble in organic solvents and compounds soluble in water such as inorganic salts. The reaction can be accomplished in a biphasic system of an inexpensive nonpolar aprotic solvent and water without using DMSO or DMF which are high-polar solvents. A phase-transfer catalyst is soluble in both solvents, and it carries anions of inorganic salts into organic solvents and returns them into the water phase. Reactions usually progress under mild conditions with easy work-up procedures. For this reason, they are also used industrially. Typical phase-transfer catalysts are quaternary ammonium salts, crown ethers, and phosphonium compounds etc. Reaction examples are shown as follows.1-4)

The asymmetric synthesis is realized using optically-active phase-transfer catalysts. The asymmetric synthesis using the cinchona alkaloid derivative as a phase-transfer catalyst was reported in the 1980s.5) Shibasaki et al. succeeded in the total synthesis of cylindricine C involving the asymmetric Michael addition catalyzed by tartaric acid derivatives.6) In this section, we introduce the cinchona alkaloid derivatives and the tartaric acid derivatives as the asymmetric phase-transfer catalysts.

Chiral Phase-Transfer Catalysts

Chiral Phase-Transfer Catalysts

Cinchona Alkaloid Derivatives

B1683 B1683 B1689 B1689 B1684 B1684
B1685 B1685
B1683 N-Benzylcinchonidinium Chloride [Chiral Phase-Transfer Catalyst]
B1689 N-Benzylcinchoninium Chloride [Chiral Phase-Transfer Catalyst]
B1684 N-Benzylquinidinium Chloride [Chiral Phase-Transfer Catalyst]
B1685 N-Benzylquininium Chloride [Chiral Phase-Transfer Catalyst]
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Tartaric Acid Derivatives

D3475 D3475 D3476 D3476
D3475 6,10-Dibenzyl-N,N'-dimethyl-N,N,N',N'-tetrakis(4-methylbenzyl)-1,4-dioxaspiro[4.5]decane-(2R,3R)-diylbis(methylammonium) Tetrafluoroborate [=(R,R)-TaDiAS-2nd]
D3476 6,10-Dibenzyl-N,N'-dimethyl-N,N,N',N'-tetrakis(4-methylbenzyl)-1,4-dioxaspiro[4.5]decane-(2S,3S)-diylbis(methylammonium) Tetrafluoroborate [=(S,S)-TaDiAS-2nd]
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Quaternary Ammonium Compounds


Crown Ethers


Phosphonium Compounds


Pyridinium Compounds


Viologens

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Literature

1) H. H. Freedman, R. A. Dubois, Tetrahedron Lett., 1975, 16, 3251 [DOI].
2) D. Landini, F. Rolla, Synthesis, 1974, 565.
3) F. L. Cook, C. W. Bowers, C. L. Liotta, J. Org. Chem., 1974, 39, 3416 [DOI].
4) C. M. Starks, J. Am. Chem. Soc., 1971, 93, 195 [DOI].
5) M. J. O'Donnell, W. D. Bennett, S. Wu, J. Am. Chem. Soc., 1989, 111, 2353 [DOI].
6) T. Shibuguchi, H. Mihara, A. Kuramochi, S. Sakuraba, T. Ohshima, M. Shibasaki, Angew. Chem. Int. Ed., 2006, 45, 4635 [DOI]; H. Mihara, T. Shibuguchi, A. Kuramochi, T. Ohshima, M. Shibasaki, Heterocycles, 2007, 72, 421 [DOI].
7) Review: Phase-Transfer Catalysts M. Makosza, Pure Appl. Chem., 2000, 72, 1399 [DOI]; J. M. McIntosh, J. Chem. Educ., 1978, 55, 235; P. Varughese, J. Chem. Educ., 1977, 54, 666; G. W. Gokel, H. D. Durst, Synthesis, 1976, 168 [DOI]; A. C. Knipe, J. Chem. Educ., 1976, 53, 618; J. Dockx, Synthesis, 1973, 441 [DOI]. Asymmertic Phase-Transfer Catalysts　K. Nagasawa, Farumashia, 2003, 39, 670; K. Maruoka, T. Ooi, Chem. Rev., 2003, 103, 3013 [DOI].

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