The Regioisomeric Triphenylaminoethanols–Comparison of their Efficiency in Enantioselective Catalysis
作者:Manfred Braun、Ralf Fleischer、Brigitte Mai、Marc-André Schneider、Stefan Lachenicht
DOI:10.1002/adsc.200303178
日期:2004.3
Both enantiomers of the novel amino alcohol (R)- and (S)-2 are prepared from the corresponding enantiomer of the mandelic acid-derived ethanediol 3. The regioisomeric amino alcohols 1 and 2 are converted into the imines 7 and 8, respectively. Titanium complexes 9 and 10 derived therefrom are used as catalysts for the addition of diethylzinc to benzaldehyde and yield the alcohol 11 in up to 92% ee.
新型氨基醇(R)-和(S)-2的两种对映体均由扁桃酸衍生的乙二醇3的相应对映体制备。区域异构的氨基醇1和2分别转化为亚胺7和8。由其衍生的钛络合物9和10用作催化剂,用于将二乙基锌加成到苯甲醛中,并产生高达92%ee的醇11。另一方面,氯取代的钛络合物14和15能够介导二酮16的Torgov环化反应,得到雌酮衍生物17。在两个反应中,新的氨基醇2衍生的钛配合物10和15都比基于区域异构氨基醇1的配合物9和14具有更高的对映选择性。