The fixation of bis(2-pyridylimino)isoindolato (BPI) ligands to dendritic carbosilanes

Abstract

Bis(2-pyridylimino)isoindolato (BPI) ligands, containing an alkynyl linker unit which allows their fixation to carbosilane dendrimers and dendrons, were synthesized by reaction of 4-nitrophthalodinitrile with 4-butynol giving the phthalodinitrile derivative containing the linker. These were subsequently reacted with two molar equivalents of 2-amino-4-methylpyridine and 2-amino-4-(t)butylpyridine yielding the respective BPI protioligands 2a and 2b. Lithiation with LDA and reaction with Si-Cl or Si-OTf (OTf=triflate) end groups in core or peripheral positions of dendritic carbosilanes gave the endodendrally and expdendrally functionalized dendrimers. Among these the first and second generation dendrimers [G-1](8-exo)-4-[C[triple bond, length as m-dash]CCH2CH2O]-10-MeBPI (8), [G-1]12-exo-4-[C[triple bond, length as m-dash]CCH2CH2O]-10-MeBPI (9) and [G-2](16-exo)-4-[C[triple bond, length as m-dash]CCH2CH2O]-10-MeBPI (10) were synthesized and fully characterized. The functional dendrimers were metallated by reaction with [(PhCN)2PdCl2] in dichloromethane to give the corresponding pallada-dendrimers.

Carbosilane Dendrons Containing a P-Stereogenic Phosphine at the Focal Point. Catalytic Behavior of Their Allylpalladium Complexes in the Asymmetric Hydrovinylation of Styrene

“…The chloro-terminated dendrons 5 and 7 were then treated with BrMgMe to give the species 8 and 9 , containing methyl end groups. The functionalization of the latter molecules at the focal point was achieved by using a previously successful method. , In this, the phenyl group is selectively converted to a highly reactive triflato group, which in turn is readily substituted by a number of nucleophiles. The acidolytic cleavage of the Si−phenyl units in 8 or 9 was carried out using trifluoromethanesulfonic acid in a 1:1 molar ratio at 0 °C in CH 2 Cl 2 .…”

“…Enantiomeric excesses were determined by GC on a Hewlett-Packard 5890 Series II gas chromatograph (30 m Chiraldex DM column) with a FID detector. [Pd(η 3 -2-Me-C 3 H 4 )(μ-Cl)] 2 , P-BH 3 , 2 , 4 − 6 , and 12 were prepared as previously described. ,, Other reagents were used as received from commercial suppliers. …”

“…This product was prepared by following literature procedures , with some experimental modifications. To a stirred solution in thf of MeMgCl (3 M, 50 mL, 150.0 mmol) at 0 °C, a solution of 5 (6.70 g, 10.6 mmol, 100 mL of thf) was added, drop by drop, for 30 min.…”

Dendrimers Derived from 1 → 3 Branching Motifs

“…Gade et al surface-functionalized Si[(CH 2 ) 3 Si[(CH 2 ) 3 SiMe 2 Cl] 3 ] 4 with 4-(3-butynoxy)-10-methyl-bis(2-pyridinylimino)isoindolate via an alkynyl linker; these terminal moieties were subsequently reacted with [PdCl 2 (PhCN) 2 ] to generate the pallada-dendrimers.…”

Functionalisation of the 1,3-bis(2-pyridylimino)isoindole (BPI) Ligand via Esterification

“…1 Among the acyclic polydentate ligands, bis(pyridylimino)isoindole (BPI ) derivatives have been the focus of interest in oxidation chemistry. [2][3][4][5][6][7] The BPI-transition metal catalysed oxidations generally tend to be unselective and it is therefore of interest whether the modification of the ligands by variation of their peripheral substitution pattern [8][9][10][11] and the variation of the oxidising agent may enable more selective transformations. 12 Recently, DNA-binding properties of the cobalt(III) complex of 1,3-bis(2-pyridylimino)isoindoline have been investigated as an example of biological application as well as catalytic properties.…”