Enantioselective Synthesis of β-Nitrophosphonates Using Immobilized Quinine Organocatalyst on Mesoporous SBA-15 as an Efficient Recyclable Catalyst

摘要

Quinine (QN) organocatalyst immobilized on mesoporous SBA-15 was synthesized by radical polymerization method. The characterization of the synthesized heterogeneous organocatalyst QN-SBA-15 (4 b) was accomplished by various physico-chemical methods to confirm the successful loading of quinine organocatalyst over SBA-15 material. The heterogeneous organocatalyst 4b was used for asymmetric Michael addition of diphenylphosphite to nitroalkenes. In contrast to its homogeneous analogue, the catalytic activity of 4b was significantly improved as revealed by high enantioselectivity (98%) and yield (92%) of β-nitro phosphonates when molecular sieve was used as an additive. Moreover, the catalyst was recyclable for five cycles with retention of enantioselectivity and yield.