Highly Effective Chirality Controlling Systems.

1.手性2-恶唑烷酮和2-咪唑烷酮助剂。采用环二烯与2-恶唑酮和2-咪唑酮[4+2]环加成的方法合成了立体拥挤的2-恶唑烷酮和2-咪唑烷酮对映体，作为有效的手性助剂。揭示了这些助剂在烷基化反应、Diels-Alder反应、michael反应和醛醇反应等不对称合成反应中的应用。构象固定的2-氨基醇。上面提到的2-恶唑烷酮被水解成具有合成意义的构象固定的2-氨基醇。(1) N，N-二烷基氨基醇和N-磺酰氨基醇在ZnEt_2催化醛的乙化反应中同样有效，但表现出完全相反的对映选择性。(2) n -磺酰基氨基醇的锂盐以近乎完美的非对映选择性将中二羧酸酯裂解为半酯。相反，锌盐与酸酐反应的选择性相反。

1.Chiral 2-Oxazolidinones and 2-Imidazolidinones Auxiliaries.Both enantiomers of sterically congested 2-oxazolidinones and 2-imidazolidinones, which served as efficient chiral auxiliaries, were synthesized by [4+2] cycloaddition of cyclic dienes with 2-oxazolone and 2-imidazolone. The utilities of these auxiliaries in asymmetric synthetic reactions such as alkylations, the Diels-Alder reactions, michael reactions and aldol reactions were revealed.2.Conformationally Fixed 2-Amino Alcohols.The 2-oxazolidinones, mentioned above, were hydrolyzed to conformationally fixed 2-amino alcohols of synthetic significance.(1) N,N-Dialkylamino alcohols and N-sulfonylamino alcohols served as equally effective catalysts in ethylation of aldehydes with ZnEt_2, but showed completely reversed enantioselectivity.(2) Lithium salts of N-sulfonylamino alcohols cleaved meso-dicarboxylic anhydrides to the half esters with almost perfect diastereoselectivity. In contrast, zinc salts reacted with the anhydrides with opposite selectivity.