A tandem Heck–aza-Michael addition protocol for the one-pot synthesis of isoindolines from unprotected amines

A palladacycle-catalyzed tandem Heck-intramolecular aza-Michael reaction protocol has been developed for the one-pot synthesis of 1-substituted isoindolines from N-unprotected 2-bromobenzylamines and acrylates with high yields

A one-pot diastereoselective self assembly of C-stereogenic copper(I) diphosphine clusters

C-chirogenic diphosphine-based clusters with 8-membered “chairlike” Cu4Cl4L2 and 12-membered “drumlike” Cu6Cl6L3 (L = diphosphine) frameworks were prepared in one-pot syntheses from chiral diphosphines, which were generated in situ via the double hydrophosphination reaction in excellent enantio- and diastereoselectivity. Excellent control over the final molecular architecture of the cluster (drum vs chair) could be achieved by the judicious selection of the source of the copper atoms employed in the synthetic protocol. Each cluster was characterized by single-crystal X-ray crystallography, 1H, 13C, and 31P{1H} NMR spectroscopy. The synthesized clusters were found to exhibit catalytic activity in the hydroboration reaction of α,β-unsaturated enones with excellent yields albeit with low enantioselectivity.Accepted versio

Domino cyclization–alkylation protocol for the synthesis of 2,3-functionalized indoles from o-alkynylanilines and allylic alcohols

A practical and efficient protocol for the one-pot synthesis of 2,3-substituted indoles was developed via a palladacycle catalyzed domino cyclization–alkylation reaction involving 2-alkynylanilines and allylic alcohols under mild conditions without any additives

Palladacycle-catalyzed asymmetric hydrophosphination of enones for synthesis of C*- and P*-chiral tertiary phosphines

A highly reactive and stereoselective hydrophosphination of enones catalyzed by palladacycles for the synthesis of C*- and P*-chiral tertiary phosphines has been developed. When Ph2PH was employed as the hydrophosphinating reagent, a series of C*-chiral tertiary phosphines were synthesized (C*–P bond formation) in high yields with excellent enantioselectivities, and a single recrystallization provides access to their enantiomerically pure forms. When racemic secondary phosphines rac-R3(R4)PH were utilized, a series of tertiary phosphines containing both C*- and P*-chiral centers were generated (C*–P* bond formation) in high yields with good diastereo- and enantioselectivities. The stereoelectronic factors involved in the catalytic cycle have been revealed

New thioether–dithiolate complexes of Cp∗Ir and some reactivity features

The reaction of [Cp∗IrCl2]2 (Cp* = η5 − C5Me5) with the tridentate 3-thiapentane-1,5-dithiolate ligand, S(CH2CH2S−)2 (tpdt), led to the formation of [Cp∗Ir(η3 − tpdt)] (1) in 81% isolated yield. Subsequent reactions of 1 with [Cp∗IrCl2]2 in 2:1 and 1:1 molar equiv ratios resulted in the formation of [Cp∗Ir(μ − η2:η3 − tpdt)Cp∗IrCl][PF6] (2) and [Cp∗Irμ − η2:η3 − tpdt)Cp∗IrCl][Cp∗IrCl3] (3) in 86 and 79% yields, respectively, based on 1, whereas the reactions of 1 with [(COD)IrCl]2 (COD = 1,5-cyclooctadiene) in 2:1 and 1:1 molar equiv ratios resulted in the formation of the homo-bimetallic derivatives Cp∗Ir(μ − η1:η3 − tpdt)(COD)IrCl (4) (92% yield) and [Cp∗Ir(μ − η2:η3 − tpdt)(COD)Ir] [(COD)IrCl2] (5) (82% yield). Reactions between 1 and [(COD)RhCl]2, yielded the hetero-bimetallic derivatives Cp∗Ir(μ − η1:η3 − tpdt)(COD)RhCl (6) and [Cp∗Ir(μ − η2:η3 − tpdt)(COD)Rh][(COD)RhCl2] (7), in 92 and 93% yields, respectively. The reaction of 1 with methyl iodide gave mono-methylated derivative [Cp∗Ir(η3-C4H8S3Me)]I (8) (93% yield). All these compounds have been comprehensively characterized

Palladacycle-catalyzed tandem allylic amination/allylation protocol for one-pot synthesis of 2-allylanilines from allylic alcohols

An efficient methodology involving the predominant formation of CC bonds is described for the first direct synthesis of 2-allylanilines from allylic alcohols via a one-pot tandem allylic amination/allylation protocol catalyzed by a palladacycle under mild conditions without the requirement for additional activators

Evaluation of palladacycles as a non-rhodium based alternative for the asymmetric conjugate 1,4-addition of arylboronic acids to α,β-unsaturated enones

The asymmetric conjugate 1,4-addition of arylboronic acids to α,β-unsaturated carbonyl compounds is an extremely versatile and widely used organic transformation. While the rhodium(I)-catalysed reaction has been thoroughly explored, the asymmetric palladium-catalysed protocol is far less developed and understood, particularly with acyclic enones as substrates. Herein, we report the systematic evaluation of a series of metallacycles for this reaction and the conjugate addition of arylboronic acids to a wide range of α,β-unsaturated enones, catalysed by an easily accessible and robust chiral phosphapalladacycle in high yields and enantioselectivities

One-pot β-alkylation of secondary alcohols with primary alcohols catalyzed by ruthenacycles

A ruthenacycle-catalyzed one-pot β-alkylation of secondary alcohols with primary alcohols is described. A survey of four C–N chelate ruthenacycles synthesized via the cyclometallation reaction of phenylmethanamine, N-methylphenylmethanamine, N,N-dimethylphenylmethanamine, and naphthalen-1-ylmethanamine with [(η6-C6H6)RuCl2]2 was undertaken. All four complexes were found to be active with the phenylmethanamine-based ruthenacycle showing the best combination of reactivity and product selectivity among the four. An expanded scope of substrates was also studied with the inclusion of unsaturated primary alcohols. The reactivity trend observed gave insights into the role of hydrogen bonding in the catalytic mechanism involving transfer hydrogenation between the substrates and the transition metal catalyst

Intermolecular insertion of dialkynylphosphanes into the M–C bond of cyclopalladated rings through activation by cyclometallated amines

A series of chiral ortho-platinated and -palladated complexes derived from N,N,α-trimethylbenzylamine has been prepared. The dialkynylphosphane PhP(C CMe)2 coordinated regiospecifically as a P M monodentate ligand to these cyclometallated units in the positions trans to the nitrogen donors of the metallacycles. Upon introduction of selected chirality on the benzylamine unit and subsequent monitoring by using NMR spectroscopy, the P Pt bond was found to be thermodynamically stable and kinetically inert. The P Pd bond must be kinetically labile since the palladium complexes readily undergo a facile ligand redistribution process. Nevertheless, both ortho-metallated units activated one of the C C bonds towards an intermolecular Pd–C bond insertion reaction into another cyclopalladated ring. No intramolecular insertion reaction occurred within the same molecule. Coordination of PhP(C CMe)2 to the ortho-palladated unit also protected the organopalladium ring from intermolecular attack by other coordinated dialkynylphosphanes. The Pt–C bonds in cycloplatinated rings are not reactive toward the insertion reaction, although they are good reaction activators for coordinated dialkynylphosphanes

Asymmetric construction of a ferrocenyl phosphapalladacycle from achiral enones and a demonstration of its catalytic potential

A new approach toward ferrocenyl phosphapalladacycle construction from achiral enones via asymmetric hydrophosphination and subsequent diastereoselective C–H activation is described. Its catalytic efficacy toward C–C bond formation is subsequently illustrated.MOE (Min. of Education, S’pore)Accepted versio