Cellulose as a source of new chiral inductors for asymmetric synthesis

MARÍA C. BOTTA; VALERIA CORNE; DAVID F. LLOMPART; MARÍA M. ZANARDI; ARIEL M. SAROTTI; ALEJANDRA G. SUÁREZ; ROLANDO A. SPANEVELLO

Montreal

Otro; Summer School on Green Chemistry and Sustainable Energy.; 2011

American Chemical Society

Biomass is a widely available raw material which has been recognized as an important source of fuels and chemical products. By far, carbohydrates are the major annually renewable biofeedstocks from which to develop viable organic chemicals that can compete or eventually replace those derived from fossil sources.Cellulose, is the most common organic compound on Earth. So the generation of useful chemicals from cellulose or cellulosic waste materials is of great interest.   Levoglucosenone (1) is a versatile and readily available member of the carbohydrate derived chiral pool, which has been used as chiral synthon in the synthesis of a wide variety of compounds. As part of our program on the pyrolytic conversion of cellulose waste into high value chemicals, we have been concerned with the synthetic application of levoglucosenone as a chiral building block in the development of new asymmetric inductors.Conventional pyrolysis of cellulose or cellulose-containing materials such as waste paper is typically used to generate but microwave  irradiation of microcrystalline cellulose was recently found to be also effective.We have developed new chiral auxiliaries and catalysts derived from cellulose in a simple and efficient way. The amino alcohols demonstrated to be very good catalysts for the enantioselective alkylation of benzaldehyde with diethylzinc. The chiral auxiliaries have shown be excellent inductors in asymmetric Diels-Alder reaction. Preliminary studies of asymmetric epoxidation reactions using the chiral ketones showed the factibility of this methodology, which is in process to be optimized. These results, in addition to the fact that the starting material is inexpensive, make these systems excellent models to be further employed in other asymmetric reactions.