A case of highly diastereoselective addition to unsymmetrical ketones:lk-addition of (2-alkenyl)triphenoxytitanium derivatives
作者:Dieter Seebach、Leo Widler
DOI:10.1002/hlca.19820650704
日期:1982.11.3
(2-Butenyl)-, (4-methyl-2-pentenyl)-, and (2-heptenyl)triphenoxytitanium (2a–c) add to dialkyl, alkyl aryl-, and alkinyl aryl ketones to give high yields of tertiary homoallylic alcohols (5–12), which are diastereomerically enriched up to 98%. Configurational assignment by degradation of two of the products to olefins 15 and 18 - through β-hydroxy acids 13 and 16 and β-lactones 14 and 17 - leads to
(2-丁烯基)-,(4-甲基-2-戊烯基)-和(2-庚烯基)三苯氧基钛(2a - c)加到二烷基,烷基芳基和炔基芳基酮中,可得到高产率的叔均烯丙基醇(5 – 12),它们的非对映异构体富集度高达98%。通过两种产物通过β-羟基酸13和16以及β-内酯14和17降解为烯烃15和18的构型分配,导致提出了一种通用的机理并提出了该化合物的相对主题1k的规格。流程(方案5)。烯丙基钛化合物2可以用作d 2-试剂(参见d 2-合成子II和醛醇型结构1)。