Diastereo‐ and Enantioselective Direct Aldol Reactions in Aqueous Medium: A New Highly Efficient Proline‐Sugar Chimeric Catalyst

Abstract

A new synthetic catalyst, capable of acting like an enzyme in the accomplishment of direct aldol reactions, is presented. Excellent results, in terms of chemical yields and diastereo-/ enantiomeric ratios, are reported for the catalyzed additions of cyclohexanone to variously substituted benzaldehydes.

Stereoselective Aldol Reaction in Aqueous Solution Using Prolinamido-Glycosides as Water-Compatible Organocatalyst

“…Water is known to inhibit the stereocontrol by interrupting hydrogen bonds of the stabilized transition state. Since proline and the analogs have shown decreased selectivity in water and do not seem to act as an aldolase [4] [5], development of water-compatible organocatalysts has been of interest, especially for prebiotic synthesis of carbohydrates [6]- [10]. In previous study, amino acyl sugar derivatives have demonstrated as water compatible organocatalysts, and prolinamido-glycosides, methyl 2-(L-prolyl)amido-α-D-glucopyranoside 1 and methyl 2-(D-prolyl)amido-α-D-glucopyranoside 2, offer useful potential as catalysts for aqueous aldol reaction [11].…”

Novel synthesis of carbohydrate-derived organocatalysts and their application in asymmetric aldol reactions

“…Recently, we have developed a new type of carbohydrate-derived prolinamide organocatalyst, which is capable of catalyzing asymmetric aldol reaction, and a remarkably better catalytic performance was provided by the reactions in terms of productivity (up to 98%), diastereoselectivity (anti/syn 99:1) and enantioselectivity (up to 99%) in water [25]. Independently and almost simultaneously, Pedatella and coworkers [26]reported a new synthetic catalyst, which were prepared by O-TBDPS D-glucosamine coupled with L-proline, acting as an efficient organocatalyst in the accomplishment of direct aldol reactions. Good chemical yields, as well as diastereomeric and enantiomeric ratios, were reported for the catalyzed additions of cyclohexanone and acetone to variously substituted benzaldehydes [27].…”

d-Fructose-derived β-amino alcohol catalyzed direct asymmetric aldol reaction in the presence of p-nitrophenol

“…[1][2][3][4][5][6][7][8][9] Most of these catalysts, with attached other chiral moieties such as acyl groups, 1 proline, 2,4-8 or aminoacyl groups, 3 have been used as organocatalysts in the direct asymmetric aldol process. [1][2][3][4][5][6][7][8][9] Most of these catalysts, with attached other chiral moieties such as acyl groups, 1 proline, 2,4-8 or aminoacyl groups, 3 have been used as organocatalysts in the direct asymmetric aldol process.…”