Cracked under strain: Strained allylic cyclobutanols and cyclopropanols readily undergo a ring expansion described by the title rearrangement. This reaction is promoted by catalytic amounts of 1 and displays high tolerance with respect to the substrate scope. The corresponding β‐fluoro spiroketone products are isolated in high yields and with excellent stereoselectivities. EDG=electron‐donating group
A New Biarylphosphine Ligand for the Pd-Catalyzed Synthesis of Diaryl Ethers under Mild Conditions
作者:Luca Salvi、Nicole R. Davis、Siraj Z. Ali、Stephen L. Buchwald
DOI:10.1021/ol202955h
日期:2012.1.6
A new bulky biarylphosphine ligand (L8) has been developed that allows the Pd-catalyzed C–O cross-coupling of a wide range of aryl halides and phenols undermilderconditions than previously possible. A direct correlation between the size of the ligand substituents in the 2′, 4′, and 6′ positions of the nonphosphine containing ring and the reactivity of the derived catalyst system was observed. Specifically
An efficient kineticresolution of sulfoximines with enals was realized using chiral N-heterocyclic carbene (NHC) catalysts. The stereoselective amidation proceeds without additional acyl transfer agent. Both enantiomers of the sulfoximines can be obtained with excellent ee values (up to 99% ee and -97% ee, respectively). Performing the catalysis on a gram scale allowed using the recovered sulfoximine
使用手性 N-杂环卡宾 (NHC) 催化剂实现了亚砜亚胺与烯醛的有效动力学拆分。立体选择性酰胺化无需额外的酰基转移剂即可进行。可以获得具有优异 ee 值的亚砜亚胺的两种对映异构体(分别高达 99% ee 和 -97% ee)。在 FXa 抑制剂 F 的不对称合成中使用回收的亚砜亚胺 (+)-1j 进行克级催化。
Enantioselective Oxetane Ring Opening with Chloride: Unusual Use of Wet Molecular Sieves for the Controlled Release of HCl
作者:Wen Yang、Zhaobin Wang、Jianwei Sun
DOI:10.1002/anie.201601844
日期:2016.6.6
An unprecedented enantioselectiveoxetaneopening with chloride provides access to a range of highly functionalized three‐carbon building blocks. The excellent enantiocontrol is enabled not only by a new catalyst, but also by the unusualuse of wetmolecularsieves for the controlledrelease of HCl.