Enantioselective Friedel–Crafts reactions between phenols and N-tosylaldimines catalyzed by a leucine-derived bifunctional catalyst
作者:Guo-Xing Li、Jin Qu
DOI:10.1039/c2cc31735d
日期:——
Enantioselective FriedelâCrafts reactions between phenols and N-tosylaldimines were developed using a bifunctional catalyst readily prepared from L-leucine. The chiral benzylic amine products were obtained in high yields (up to 96% yield) and good to high enantiomeric excesses (up to 95% ee).
Expedient C−H additions of heteroarenes onto aldimines were realized by a sustainable manganese catalysis manifold within a removable directing group strategy. The C−Hactivation features most user‐friendly reaction conditions, excellent chemo‐ and position‐selectivity as well as ample substrate scope. Detailed experimental mechanistic studies suggest an organometallic C−H manganesation mode of action
A highly efficient bisguanidine organocatalyst has been developed for the asymmetric Mannich‐type reaction of α‐isothiocyanato imide with N‐Ts‐protected imines (Ts=tosyl, see scheme). A series of aromatic, α,β‐unsaturated, heteroaromatic, and aliphatic imines can be converted into the desired α,β‐diamino acid derivatives in good to excellent yields with high diastereoselectivities (up to >95:5 d.r
A<i>N,N′</i>-Dioxide-Copper(II) Complex as an Efficient Catalyst for the Enantioselective and Diastereoselective Mannich-Type Reaction of Glycine Schiff Bases with Aldimines
A highly diastereo‐ and enantioselective Mannich‐type reaction of glycine Schiff base 1 has been developed by using the N,N′‐dioxide L‐CuII complex as a catalyst. Various optically active anti‐α,β‐diamino acid esters were obtained in good yields with up to 96:4 d.r. and 97 % ee. This straightforward method features a low catalyst loading and mild reaction conditions.
温和的举止!通过使用N,N'-二氧化物L- Cu II配合物作为催化剂,开发了甘氨酸Schiff碱1的高度非对映和对映选择性曼尼希型反应。以高达96:4 dr和97%ee的高收率获得了各种光学活性的抗α,β-二氨基酸酯 。这种简单的方法具有催化剂负载低和反应条件温和的特点。
(3+2) Annulation of 4‐Acetoxy Allenoate with Aldimine Enabled by AgF‐Assisted P(III)/P(V) Catalysis
AgF is capable of converting the enolate-phosphonium zwitterion into a novel silver enolate-fluorophosphorane species, which enables the development of (3+2) annulation of 4-acetoxy allenoate and aldimine via P(III)/P(V) catalysis. The proof-of-concept study has demonstrated that the silver enolate moiety offers an alternative approach to realize an asymmetric variant merely by the introduction of