Study On Reduction Of Chiral Hydroxyl (amino) Esters By Sodium Borohydride And Synthesis Of Oxazolidinone Compounds

Sodium borohydride (NaBH₄) is one of classic reducing agent, which is widely used in organic synthesis. Considering its mild, highly selective characteristics, NaBH₄ takes no effect on other functional groups except reducing aldehydes, ketones and acid chlorides. Lithium aluminum hydride was commonly used for the reduction of ester, but the shortcomings of poor selectivity and expensive makes it difficult to apply in industries. The low cost, mild nature and high chemoselectivity are some of the distinct features that make sodium borohydride one of the most popular reagents used in industry. We've got a conclusion that, sodium borohydride has advantages of good reduction, short reaction time, and high yield at temperature to o-hydroxy esters. What more important is that the reduction products is chiral vicinal diol which has important applications as the intermediate in the synthesis of chiral drug and natural product.In this study, boron atoms in the coordination ability, using NaBH₄ alone in the process of reducing the chiral hydroxyl (amino) esters, trying under a variety of conditions, we've found such esters could be well reduced in NaBH₄/THF system spending a short time. In the process of reaction, we have also found this method had an array of advantages such as mild reaction conditions, environment-friendly, shorter reation time and higher yield. We are also surprised to find a new way to synthesize oxazolidinone compounds.Oxazolidinone compounds has a wide range of applications in medicament, organic synthesis and the actual production, thus, is a very high value kind of five-membered ring compound. For Oxazolidinone compounds have a new mechanism in inhibiting bacterial protein, it is a new synthetic antibacterial medicine. In addition, 2-oxazolidinone and its derivatives are both commonly used chiral auxiliary agent, 4-substituted-2-oxazolidinone is a representation of the induction of high selectivity. Since Evans firstly developed an effective and widely used chiral auxiliary reagent, which was known as Evans reagent and has been widely applied in controlling the number of N-acylated substrating asymmetric reactions effectively, such as the aldol condensation, hydroxylation,α-amine reaction, halogenated reaction, Diels-Alder reaction and addition reaction Micheal and so on. The synthetic methods of oxazolidinone compounds is particularly important either it is used as a promising new synthetic antimicrobial agent or a highly stereoselective chiral auxiliary reagent. Early synthesis methods of oxazolidine-2-ketones mostly based on amino alcohols and phosgene as raw materials, which have amount of shortcomings such as cumbersome operations, waste in use of asolvents that is quite a waste of resources and a great pollution to the environment and so on. Thus, some scientists begin to try new synthetic methods, including the CO, CO₂ or urea was carbonyl reagent for the cyclization, together with the method of making oxazolidinones from carbon dioxide and aziridines.In conclusion, the unexpected discovery has given us a good idea to synthesise oxazolidinone compounds in one step in which the strating compounds are protected amino acid ester. The reaction synthesizes 4-substituted oxazolidinone simply with high yield under the room temperature in NaBH₄/THF system which uses amino acid ester as raw materials. There is only one step reaction in the process, for its simplisity, the whole process is clean and efficient, thus it is conducive to large-scale industrial production, as a result it can be used as a new approach of synthesizing oxazolidinone compounds to promote.