Enantioselective 1,3-Dipolar Cycloaddition Reaction of Nitrones with α,β-Unsaturated Aldehydes Catalyzed by Cationic 3-Oxobutylideneaminatocobalt(III) Complexes
complex, the enantioselective1,3-dipolarcycloaddition reaction of various nitrones with α,β-unsaturatedaldehydes afforded the corresponding isoxazolidines in high yields and with high enantioselectivities. The absolute configuration of the optically active products was determined by X-ray analysis. Reasonable explanations for the enantioselection in the present 1,3-dipolarcycloaddition reaction catalyzed
硝酮与α,β-不饱和醛的对映选择性1,3-偶极环加成反应是使用3-氧代丁基亚氨基钴配合物催化剂实现的。筛选了各种钴 (II) 和钴 (III) 配合物,发现阳离子钴 (III) 配合物与六氟锑酸盐对催化对映选择性 1,3-偶极环加成反应最有效。在六氟锑酸钴 (III) 络合物的存在下,各种硝酮与 α,β-不饱和醛的对映选择性 1,3-偶极环加成反应以高产率和高对映选择性提供相应的异恶唑烷。旋光产物的绝对构型通过 X 射线分析确定。对当前1中对映选择的合理解释,
Enantioselective 1,3-Dipolar Cycloaddition of Nitrones Catalyzed by Optically Active Cationic Cobalt(III) Complexes
cobalt(III) complexes were employed as efficient Lewis acid catalysts for the enantioselective1,3-dipolarcycloaddition reaction of alpha,beta-unsaturated aldehydes with nitrones. Excellent endo selectivities and high enantioselectivities were achieved in the cycloaddition reaction of 1-cyclopentene-1-carbaldehyde and the nitrones derived from 2-halobenzaldehyde.