Br, I, OAc, OTf) complexes, providing tertiary propargylic trifluoromethyl alcohols in high yields and with excellent chemoselectivity from a broad range of aryl‐ and more challenging alkyl‐substituted trifluoromethyl ketones (TFMKs). DFT calculations were performed to rationalize the correlation between the yield of catalytic alkynylation and the sterics of N‐heterocycliccarbenes (NHCs), expressed
Catalytic Enantioselective Alkynylation of Trifluoromethyl Ketones: Pronounced Metal Fluoride Effects and Implications of Zinc-to-Titanium Transmetallation
作者:Guang-Wu Zhang、Wei Meng、Hai Ma、Jing Nie、Wen-Qin Zhang、Jun-An Ma
DOI:10.1002/anie.201007341
日期:2011.4.4
(L1 and L2), was developed for the synthesis of both enantiomers of trifluoromethylated propargylic tertiary alcohols in high yield and enantioselectivity. Small amounts of BaF2 were found to be essential for maintaining high levels of reactivity and enantioselectivity.
Enantioselective alkynylation of trifluoromethyl ketones catalyzed by chiral Schiff bases in the presence of Me2Zn afforded the corresponding trifluoroalkynyl alcohols in up to 66 % ee.
Enantioselective Alkynylation of Trifluoromethyl Ketones Catalyzed by Cation‐Binding Salen Nickel Complexes
作者:Dongseong Park、Carina I. Jette、Jiyun Kim、Woo‐Ok Jung、Yongmin Lee、Jongwoo Park、Seungyoon Kang、Min Su Han、Brian M. Stoltz、Sukwon Hong
DOI:10.1002/anie.201913057
日期:2020.1.7
Cation-binding salen nickel catalysts were developed for the enantioselective alkynylation of trifluoromethyl ketones in high yield (up to 99 %) and high enantioselectivity (up to 97 % ee). The reaction proceeds with substoichiometric quantities of base (10-20 mol % KOt-Bu) and open to air. In the case of trifluoromethyl vinyl ketones, excellent chemo-selectivity was observed, generating 1,2-addition
Chiral‐at‐Ruthenium Catalyst with Sterically Demanding Furo[3,2‐
<i>b</i>
]pyridine Ligands
作者:Tianjiao Cui、Jie Qin、Klaus Harms、Eric Meggers
DOI:10.1002/ejic.201801362
日期:2019.1.17
A stericallydemanding derivative of a previously introduced chiral‐at‐metal ruthenium(II) catalyst scaffold is introduced. It is composed of two bidentate furo[3,2‐b]pyridyl functionalized N‐heterocyclic carbene ligands. Their cis‐coordination generates helical chirality and a stereogenic ruthenium center. Two additional labile acetonitriles compose the catalytic site which is highly shielded by two
引入了先前引入的手性金属钌(II)催化剂支架的空间要求较高的衍生物。它由两个二齿呋喃并[3,2- b ]吡啶基官能化的N-杂环卡宾配体组成。它们的顺式配位产生了螺旋手性和一个立体的钌中心。另外两个不稳定的乙腈组成了催化位点,该位点被两个2-(叔丁基)呋喃[3,2- b ]吡啶部分高度屏蔽。报告了非外消旋钌催化剂的合成及其对2,2,2-三氟苯乙酮和五氟苯甲醛的对映选择性炔基化反应的催化性能,并将其与空间上要求不高的衍生物进行了比较。