Sythesis of chiral organocatalyst and applications

Asymmetric synthesis of chiral compounds have great importance in organic synthesis. The synthesis of optically pure compounds is one of the important areas of the synthetic chemistry for the production of pharmaceuticals, agricultural chemicals and functionalized materials, because of the necessity for these compounds in biological systems. Asymmetric catalytic reactions which include enzymes, metal catalysts and organocatalysts are considered as effective tools for the synthesis of enantiomerically pure compounds. Environmental and health regulations strongly support to non-toxic chemical processes which do not use toxic reagents. Chemical companies avoid transition metals in bulky catalytic reactions. In this sense, scientific communites continue to construct a new field in enantioselective synthesis for metal-free synthetic designs. Metal free small organic compounds that accelerate the chemical reactions in catalytical amounts are defined as organocatalysts. Organocatalysts have several advantages over metal catalysts, such as insensibility to moisture and oxygen, readily availability, low cost, and low toxicity. Especially, low toxicity makes them more attractive in the production of the pharmaceutical intermediates. Besides, asymmetric organocatalysts accomplish the reactions more effectively and attract the attention because of their operational simplicity over classic metal catalysts. The aldol reaction have been investigated intensively as one of the powerful methods for the formation of new carbon-carbon bonds, and important developments have been observed recently. Asymmetric direct aldol reaction is one of the important reactions for the production of β-hydroxycarbonyl compounds with two new stereogenic center at alpha and beta positions of carbonyl groups. Optically pure β-hydroxycarbonyl compounds are versatile precursors for the synthesis of pharmaceutically active compounds and related materials, and natural products. Until now, prolin has generally been used as catalyst in the asymmetric intermolecular aldol reaction and important transformations have been carried out. Our research is based on the idea to design new chiral organocatalyst with structural diversity to catalyze asymmetric direct aldol reaction under various reaction conditions. By this aim, synthesis of the (R)-thiazolidin-4-carboxylic acid based new chiral organocatalysts having dipeptide structure have been accomplished. The structure of these catalysts have been determined by the FTIR, 1H NMR, 13C NMR and GC-MS spectral data. In the last step, catalytic activity of the synthesized organocatalysts in the enantioselective aldol reaction was investigated. Good yields and enantioselectivities have been observed with (R)-thiazolidin-4-carboxylic acid based organocatalysts which have not been widely investigated in the literature.