Iron Phosphate Catalyzed Asymmetric Cross-Dehydrogenative Coupling of 2-Naphthols with β-Ketoesters
摘要:
Chiral iron phosphate complexes were successfully exploited for asymmetric cross-dehydrogenative coupling reactions between 2-naphthols and beta-ketoester derivatives. On the basis of kinetic studies, it is suggested that iron monophosphate complexes constitute the active catalysts that induce stereoselectivity during the carboncarbon bond-formation step.
overall yield from O-methylnaphthazarin. Highlights of the synthetic work include an Ullmann coupling and a possibly biomimetic oxidative spirocyclization for the introduction of the naphthalene ketal as well as the use of a retro-Diels-Alder reaction to unmask the reactive enone moiety in the naphthoquinone bisepoxide ring system. A novel highly bulky chiral binaphthol ligand was developed for a boron-mediated
Chiral Brønsted Acid-Catalyzed Direct Mannich Reactions via Electrophilic Activation
作者:Daisuke Uraguchi、Masahiro Terada
DOI:10.1021/ja0491533
日期:2004.5.1
It was found that the phosphoric acid derivatives of general structure 1 serve as highly effective catalysts for the direct addition of acetyl acetone to N-Boc-protected arylimines. The beneficial effects of the 3,3'-bisaryl substituents of the catalysts on the enantioselectivity are greatly appreciated, and thus 1d functions as an excellent catalyst. The Brønsted acid-catalyzed direct Mannich reactions
Chiral pyridinium phosphoramide 1·HX was designed to be a new class of chiral Brønsted acid catalyst in which both the pyridinium proton and the adjacent imide-like proton activated by the electron-withdrawing pyridinium moiety could work cooperatively as strong dual proton donors. The potential of 1·HX was shown in the enantioselectiveDiels–Alder reactions of 1-amino dienes with various dienophiles
Iodomethylzinc Phosphates: Powerful Reagents for the Cyclopropanation of Alkenes
作者:Marie-Christine Lacasse、Cyril Poulard、André B. Charette
DOI:10.1021/ja0529687
日期:2005.9.1
stereocontrol, affording the cyclopropanes of allylic and homoallylic ethers with complete conversions and up to 93% ee. A catalytic version of this reaction using 10 mol % of the chiral phosphate reagent is also disclosed.
开发了一类新的源自磷酸的类锌类化合物,并将其用于烯丙醇和醚以及未官能化烯烃的环丙烷化。使用 3,3'-二取代 BINOL 的手性磷酸可实现有效的立体控制,提供具有完全转化率和高达 93% ee 的烯丙基醚和高烯丙基醚的环丙烷。还公开了使用10mol%手性磷酸盐试剂的该反应的催化形式。
The Long-Arm Effect: Influence of Axially Chiral Phosphoramidite Ligands on the Diastereo- and Enantioselectivity of the Tandem 1,4-Addition/Fluorination
作者:Lian Wang、Wei Meng、Chuan-Le Zhu、Yan Zheng、Jing Nie、Jun-An Ma
DOI:10.1002/anie.201104565
日期:2011.9.26
Long arm of the law: The long‐armed phosphoramidite 1 was used as a catalyst for the title reaction of acyclic alkylidene β‐ketoesters with dialkylzinc and fluorinating reagents. The products, containing adjacent carbon‐ and fluorine‐substituted stereocenters, are obtained in high yield as well as diastereo‐ and enantioselectivity. NSFI=N‐fluorobenzenesulfonimide.