Enantio- and Diastereoselective Formal Hetero-Diels-Alder Reactions of Trifluoromethylated Enones Catalyzed by Chiral Primary Amines
作者:Yong-Jun Lin、Li-Na Du、Tai-Ran Kang、Quan-Zhong Liu、Ze-Qin Chen、Long He
DOI:10.1002/chem.201501897
日期:2015.8.10
Enantioselective formal hetero‐Diels‐Alderreactions of trifluoromethylated enones and 2‐amino‐1,3‐butadienes generated in situ from aliphatic acyclic enones and chiral primary amines are reported. The corresponding tetrahydropyran‐4‐ones are formed in up to 94 % yield and with up to 94 % ee. The reaction was carried out through a stepwise mechanism, including initial aminocatalytic aldol condensation
Isothiourea-mediated asymmetric Michael-lactonisation of trifluoromethylenones: a synthetic and mechanistic study
作者:Louis C. Morrill、James Douglas、Tomas Lebl、Alexandra M. Z. Slawin、David J. Fox、Andrew D. Smith
DOI:10.1039/c3sc51791h
日期:——
HBTM-2.1 promotes the catalytic asymmetric intermolecular Michael-lactonisation of arylacetic acids and trifluoromethylenones in the presence of pivaloyl chloride, giving C(6)-trifluoromethyldihydropyranones with high diastereo- and enantiocontrol (up to 95 : 5 dr and >99% ee) that are readily derivatised to diverse synthetic building blocks containing trifluoromethyl-stereogenicity. Kinetic studies indicate the reaction is first order with respect to both in situ formed mixed anhydride and catalyst concentration, with a primary kinetic isotope effect observed using α,α-di-deuterio 4-fluorophenylacetic acid, consistent with rate determining deprotonation of an intermediate acyl isothiouronium ion.
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
boronic acids to α,β-unsaturated 1,1,1-trifluoromethyl ketones affords corresponding addition products bearing a stereogenic center at the β-position in moderate to high yields and excellent enantioselectivities (up to 99% ee), without any 1,2-addition product formation. Moreover, this catalytic protocol features mild reaction conditions, a broad substrate scope, suitability for alkenylboronic acids and