Assessment of non-standard reaction conditions for asymmetric 1,3-dipolar organocatalytic cycloaddition of nitrone with alpha,beta-unsaturated aldehydes

作者：Mojzesova Melinda; Meciarova Maria; Almassy Ambroz; Marti Roger; Sebesta Radovan^*

来源：Chemical Papers, 2015, 69(5): 737-746.

DOI：10.1515/chempap-2015-0020

• dipolar cycloaddition
• ball-milling
• flow reactor
• ionic liquids
• microwave
• ultrasound

Non-standard experimental conditions can often enhance organocatalytic reactions considerably. The current study explores the effectiveness of a range of non-standard reaction conditions for the asymmetric organocatalytic 1,3-dipolar cycloaddition of a nitrone with alpha,beta-unsaturated aldehydes. The influence of ionic liquids, high-pressure conditions, ultrasound, microwave irradiation and ball-milling was tested as well as the flow process. Because of the low reactivity of the nitrone and unsaturated aldehydes in the 1,3-dipolar cycloaddition, cycloadducts were isolated in only moderate yields from the majority of experiments. However, high diastereo- and enantioselectivities were observed in ionic liquids under solvent-free conditions and in the flow reactor.

• 出版日期2015-5