Research Of Some Organocatalytic Michael-Initiated Asymmetric Domino Reaction

Some chiral organic molecule catalystsincluding bifunctional thiourea andJ rgensen-Hayashi catalyst were prepared with chiral1,2-diaminocyclohexane andproline as starting materials according to the reported procedures, which have beensuccessfully applied to promote the asymmetric S-Michael, O-Michael, C-Michael,N-Michael, P-Michael additions. Optically active compounds were prepared.In the first part, we synthesized a series of olefinic azlactone derivatives.Takemoto organocatalyst have been explored as organocatalyst forthethio-Michael/ring opening reaction of aromatic thiols witholefinic azlactones. Aseries of non-natural α-amino acid with good yields, good diastereoselectivities andgood enantioselectivities were obtained. Besides, chiral compounds could be easilyobtained by direct filtration andsimple washing procedure. In this catalytic system,gram-scale products could be easily realized.In the second part, the reaction between (E)-ethyl4-(2-hydroxyphenyl)-2-oxobut-3-enoate derivatives and α,β-unsaturated aldehydewere catalyzed by J rgensen-Hayashi catalyst. O-Michael-Hetero-Diels-Alderreaction or O-Michael-Michael-Michael-Aldol reaction were selectively realized bycontrolling temperature. Two series of chromane derivatives were obtained in goodyields, excellent diastereoselectivities and enantioselectivities.In the third part, asymmetric Michael/aromatization reaction of azlactonestoα,β-unsaturated pyrazolones was realized with isosteviol-derived thiourea asorganocatalyst. Chiral heterocyclic compounds containing both a pyrazolemotif and amasked amino acid structure were obtained in good yields with moderate to excellentenantioselectivitiesIn the fourth part, N-Michael/hemiacetalreaction between disubstitutedhydrazinesand α,β-unsaturated aldehydes has been realized with J rgensen-Hayashicatalyst as organocatalyst. Sixteen enantiomericallyenrichedpyrazolidine derivatives were obtained in moderate togood chemical yields withmoderate to excellent enantioselectivities and good diastereoselectivities.In the fifth part,Asymmetric P-Michael/Aromatization reaction ofdiarylphosphane oxides toα,β-unsaturated pyrazolones has been realized withisosteviol-derived thiourea as organocatalyst. Fifteen enantiomerically enrichedphosphorus-containing pyrazole compounds have been obtained in moderate to goodchemical yields with moderateenantioselectivities.