Novel Methods for the construction of Biologically Active Natural Products based on a chiron-synthetic strategy

我们已经recently reported novel and stereoselective methods for the homochiral construction of homochirallactam derivatives elaborated from tartaric acid, sugar, glutamic acid as a chiral pool，and demonsrtated the possibility for the total synthesis of biologically active alkaloids employing这些compouds.In this conection we wish to communicate two results that a stereoselection route toenantiomerically and diastereomerically pure pentasubstituted pyrrolidines has been developed byusing reductive deoxygenation and/or stereoselective reduction of quaternary α-hydroxy - bocpyrrolidine derivatives prepared from alkylation of the functionalized homochiral lactams. In thelatter case, especially，it could proceed through the predominant attack of H i D1 on the carbonyl function from the topface of the 6 -membered metal-chalate rather than five-membered one due to the shielding effect ofthe three large functional groups.Finally，an efficient and stereodefined process was描述为第一个asymmetric synthesis of atetrasubstituted pyrrolidine alkaloid, broussonetine C，as a potent β-galactosidase and β-mannosidase inhibitor by featuring the elaboration through thisstereoselective reduction方法。

We have recently reported novel and stereoselective methods for the construction of homochiral lactam derivatives elaborated from tartaric acid, sugar, and glutamic acid as a chiral pool, and demonsrtated the possibility for the total synthesis of biologically active alkaloids employing these compouds.In this conection we wish to communicate two results that a stereoselective route to enantiomerically and diastereomerically pure pentasubstituted pyrrolidines has been developed by using reductive deoxygenation and/or stereoselective reduction of quaternary α-hydroxy N-Boc pyrrolidine derivatives prepared from alkylation of the functionalized homochiral lactams. In the latter case, especially, it could proceed through the predominant attack of HィイD1-ィエD1 on the carbonyl function from the top face of the six-membered metal-chalate rather than five-membered one due to the shielding effect of the three large functional groups.Finally, an efficient and stereodefined process was described for the first asymmetric synthesis of a tetrasubstituted pyrrolidine alkaloid, broussonetine C, as a potent β-galactosidase and β-mannosidase inhibitor by featuring the elaboration through this stereoselective reduction method.