Yudao Ma

Enantioselective β-Boration of Acyclic Enones by a [2.2]Paracyclophane-Based N-Heterocyclic Carbene Copper(I) Catalyst

A new planar and centrally chiral bicyclic 1,2,4-triazolium salt has been synthesized from [2.2]paracyclophane and phenylglycinol. The N-heterocyclic carbene (NHC) copper(I) complex generated in situ by the reaction of the triazolium salt and Cu(2)O was an efficient catalyst for the asymmetric β-boration of acyclic enones, producing β-boryl ketones in high yields and enantioselectivities.

Knoevenagel Condensation Catalyzed by USY Zeolite

Abstract: Abstract The Knoevenagel condensation of substituted benzaldehydes with active methylene compounds was performed very efficiently by using a USY (ultrastable Y) zeolite as heterogeneous catalyst.

Application of Bidentate Oxazoline–Carbene Ligands with Planar and Central Chirality in Asymmetric β-Boration of α,β-Unsaturated Esters

A series of new oxazoline-substituted imidazolium salts based on [2.2]paracyclophane were synthesized and characterized. The new bidentate oxazoline-carbene precursor with planar and central chirality had significant advantage than the bicyclic 1,2,4-triazolium salt derived from [2.2]paracyclophane as a monodentate carbene ligand in Cu(I)-catalyzed asymmetric β-boration of α,β-unsaturated esters, giving the desired products in high enantioselectivities and yields.

An efficient catalyst system for Pd-catalyzed amination of [2.2]paracyclophanyl bromides.

A practical Buchwald-Hartwig amination of [2.2]paracyclophanyl bromides with benzhydrylideneamine is developed. The method provides a facile route to a variety of imino and amino [2.2]paracyclophanes that are otherwise not readily synthesized.

Synthesis and application of a dual chiral [2.2]paracyclophane-based N-heterocyclic carbene in enantioselective β-boration of acyclic enones

An enantioselective conjugate addition of boron to α,β-unsaturated ketones catalysed by either a N-heterocyclic carbene or a copper-carbene complex generated in situ from a new chiral bicyclic triazolium based on [2.2]paracyclophane is presented. The dual chiral carbene-copper catalyst has significant advantages over its carbene counterpart as an organocatalyst in asymmetric β-boration of acyclic enones, giving a variety of chiral β-boryl ketones in good yields and enantioselectivities. This is a successful example of employing the same N-heterocyclic carbene in one catalytic reaction as both an organocatalyst and a ligand for transition metal catalysis.

SYNTHESIS OF PLANAR CHIRAL (2.2)PARACYCLOPHANYL IMIDAZO(1,5-a) PYRIDINIUM SALTS FOR THE RHODIUM- CATALYZED ASYMMETRIC ARYLATION

Abstract Several novel flexibility-restricted imidazo[1,5-a]pyridinium triflates (abbreviated as imidazolium salts) were synthesized from (4S p,13R p)-(−)-4-amino-13-bromo[2.2]paracyclophane and pyridylaldehyde. These imidazolium salts can be used as nitrogen-containing heterocyclic carbene precursors in asymmetric catalysis and here they are applied in the Rh-catalyzed asymmetric 1,2-addition of arylboronic acids to aldehydes. After optimizing the catalytic situations and testing a series of substrates, moderate enantioselectivity and good yield were obtained. GRAPHICAL ABSTRACT

Synthesis of Cyclophanes with Planar and Helical Chirality

Novel helical macrocyclic imines derived from planar chiral [2.2]paracyclophane were synthesized. The chiroptical properties of the enantiopure compounds were investigated and their absolute configurations were assigned.

[2.2]Paracyclophane-based carbene–copper catalyst tuned by transannular electronic effects for asymmetric boration

A series of planar chiral carbene–copper complexes based on the [2.2]paracyclophane backbone with a pseudo-ortho substitution pattern have been synthesized and applied to asymmetric β-boration of α,β-unsaturated esters. As a result, transannular electronic effects of the substituent of the chiral catalyst have significant influence on the catalytic performance. A variety of chiral β-hydroxyl esters were obtained in excellent enantioselectivities (up to 97% ee) and yields (up to 99%).

[2.2]Paracyclophane-based N-heterocyclic carbene as efficient catalyst or as ligand for copper catalyst for asymmetric α-silylation of N-tosylaldimines

A new series of chiral bicyclic 1,2,4-triazolium salts with various substituents in the pseudo-ortho position of the [2.2]paracyclophane skeleton has been successfully synthesized and applied to enantioselective α-silylations of N-tosylaldimines. The dual role of the new carbene precursor as an organocatalyst and as a ligand of the copper catalyst in the asymmetric silylation were investigated. The chiral carbene–copper catalyst has significant advantages over its carbene counterpart as an organocatalyst, affording the corresponding α-silyl amines in 77–99% yields over 20 examples and with 76–98% ee. In addition, the transannular electronic effects of the substituents in the pseudo-ortho position of the [2.2]paracyclophane skeleton were also discussed.

An Economic Approach to Chiral Thiosulfinates by Enantioselective Oxidation with Hydroperoxide

Abstract Some novel chiral ligands and VO(acac)2 were utilized to catalytic asymmetric oxidation of disulfides. The optically active thiosulfinates were obtained.