Efficient 1,8- and 1,9-asymmetric inductions in the Grignard reaction of δ- and ɛ-keto esters of 1,1′-binaphthalen-2-ols with an oligoether tether as the 2′-substituent: application to the synthesis of (−)-malyngolide
Catalyticasymmetric vinylogous Mukaiyama reactions on ketones, leading to the formation of alpha,beta-unsaturated lactones with tertiary alcohols, have been described (11 examples, up to 93% ee). This methodology has been applied in a formal enantioselective synthesis of taurospongin A (12 steps, 6% overall yield).
Binding the anion: A highly enantioselectiveiodolactonization of 5‐hexenoic acids has been achieved using a tertiary aminourea‐catalyst (see scheme). The use of catalytic iodine in this process is critical to enhancing both the reactivity and enantioselectivity of the stoichiometric I+ source. The mechanism is proposed to involve binding of an iodonium imidate intermediate by the H‐bond donor catalyst
结合阴离子:使用叔氨基脲催化剂实现了 5-己烯酸的高度对映选择性碘内酯化(参见方案)。在该过程中使用催化碘对于提高化学计量 I +源的反应性和对映选择性至关重要。该机制被认为涉及通过氢键供体催化剂结合亚胺酸碘鎓中间体。
A facile synthesis of optically active lactones using benzyl-3,6-anhydro glucofuranoside as chiral auxiliary
作者:Vijay Nair、Jaya Prabhakaran、Tesmol G. George
DOI:10.1016/s0040-4020(97)10005-9
日期:1997.11
A highly enantioselective synthesis of γ- and δ-lactones using an anhydrofuranoside derived from D-glucose as chiralauxiliary is described.
作者:Rajat Maji、Santanu Ghosh、Oleg Grossmann、Pinglu Zhang、Markus Leutzsch、Nobuya Tsuji、Benjamin List
DOI:10.1021/jacs.3c01404
日期:2023.4.26
Despite recent advancements in the development of catalyticasymmetric electrophile induced lactonization reactions of olefinic carboxylic acids, the archetypical hydrolactonization has long remained an unsolved and well-recognized challenge. Here, we report the realization of a catalyticasymmetric hydrolactonization using a confined imidodiphosphorimidate (IDPi) Brønsted acid catalyst. The method
尽管最近在催化不对称亲电试剂诱导的烯烃羧酸内酯化反应的发展方面取得了进展,但原型加氢内酯化长期以来一直是一个未解决且公认的挑战。在这里,我们报告了使用限制性亚氨基二磷酸酯 (IDPi) 布朗斯台德酸催化剂实现催化不对称加氢内酯化。该方法操作简单、可扩展且与多种底物兼容。它的潜力通过倍半萜烯 (−)-boivinianin A 和 (+)-gossonorol 的简明合成得到展示。通过深入的物理化学和 DFT 分析,我们得出了该反应的机理和对映选择性的细微差别。
709. Partial asymmetric synthesis with keto-esters. Part I