3-取代2,4-二氨基酸及其多取代吡咯烷衍生物的不对称合成

convenient and efficient way for the highly diastereoselective synthesis of 3-substituted 2, 4-diaminobutyric acids and pyrrolidines containing multichiral centers has been well developed. Michael addition of chiral tricyclic iminolactones 1 and 2 to nitroalkenes afforded the adducts in good yields (up to 95%) and excellent diastereoselectivities (up to dr>99:1) when titanium(IV) isopropoxide was used. Configuration of the second new stereocenter was decided by the substitution of nitroalkene. Selective reduction and hydrolysis of the Michael adducts furnished the desired -substituted , -diaminobutyric acids in good yields and high enantiomeric excesses (>99% ee). Synthesis of pyrrolidines containing multichiral centers has also been accomplished in good to excellent yields and diastereoselectivities under mild conditions via Michael-Mannich tandem reactions using Cu(OTf)2 or AgOTf as an activating reagent for aliphatic nitroalkenes..