Asymmetric Annulations Of The MBH-Alcohol Derivatives

Asymmetric synthesis has deemed as an important research field in organic chemistry,and asymmetric organocatalysis has emerged as a research hotspot in the field of organocatalysis in recent years.With the development of organocatalysis,phosphine reagents has gradually become more and more popular in the field of organocatalytic.In particular,chiral phosphine catalysts have developed vigorously in recent years due to their mild reaction conditions,high reactivity and wide application range,and have been applied to a series of different types of asymmetric catalytic reactions,such as addition reaction,annulations reaction,Rauhut-Currier(RC)reaction and Morita-Baylis-Hillman(MBH)reaction.MBH alcohol derivatives(MBHADs)has regarded as rare synthetic blocks in organic synthesis,especially chiral phosphine-catalyzed MBHADs are widely used in annulation.Generally,MBHADs are often used as C3 synthons in many cycloaddition,and it is rarely reported as C1 synthons in cyclization.Based on this,the research contents of this paper are as following.We overcame the restriction to successfully develop a chiral phosphine catalysed asymmetric [1+4] annulation of MBH carbonates with 2-enoylpyridines.We designed a series of optitally active 2,3-dihydrofurans containing pyridine groups.We applyed MBH carbonates and 2-enoylpyridines as the annulation substrates,and used(-)-1,2-bis[(2R,5R)-2,5-dimethylphospholano]benzene as the annulation catalysts.We furnished the corresponding target products in 30%-85% yield with 83%-95% ee and >20:1 dr.We overcame the restriction to successfully develop a chiral phosphine catalysed asymmetric [1+4] annulation of MBH carbonates with 2-enoylpyridine N-oxides.We designed a series of optitally active 2,3-dihydrofurans containing pyridine N-oxides groups.We applyed MBH carbonates and 2-enoylpyridines N-oxides as the annulation substrates,and used 1,2-bis[(2R,5R)-2,5-dimethylphospholano]benzene monoxide as the annulation catalysts.We furnished the corresponding target products in 31%-96% yield with 96%->99% ee and >20:1 dr.