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Hydrophobic substituent effects on proline catalysis of aldol reactions in water.

ABSTRACT: Derivatives of 4-hydroxyproline with a series of hydrophobic groups in well-defined orientations have been tested as catalysts for the aldol reactions. All of the modified proline catalysts carry out the intermolecular aldol reaction in water and provide high diastereoselectivity and enantioselectivity. Modified prolines with aromatic groups syn to the carboxylic acid are better catalysts than those with small hydrophobic groups (1a is 43.5 times faster than 1f). Quantum mechanical calculations provide transition structures, TS-1a(water) and TS-1f(water), that support the hypothesis that a stabilizing hydrophobic interaction occurs with 1a.

SUBMITTER: Zhao Q

PROVIDER: S-EPMC3589585 | biostudies-literature | 2012 May

REPOSITORIES: biostudies-literature

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Hydrophobic substituent effects on proline catalysis of aldol reactions in water.

Zhao Qingquan Q Lam Yu-hong YH Kheirabadi Mahboubeh M Xu Chongsong C Houk K N KN Schafmeister Christian E CE

The Journal of organic chemistry 20120508 10

Derivatives of 4-hydroxyproline with a series of hydrophobic groups in well-defined orientations have been tested as catalysts for the aldol reactions. All of the modified proline catalysts carry out the intermolecular aldol reaction in water and provide high diastereoselectivity and enantioselectivity. Modified prolines with aromatic groups syn to the carboxylic acid are better catalysts than those with small hydrophobic groups (1a is 43.5 times faster than 1f). Quantum mechanical calculations ...[more]

PMID: 22500641

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