Modular functionalized polyphosphines for supported materials: previously unobserved³¹P-NMR «through-space» ABCD spin systems and heterogeneous palladium-catalysed C–C and C–H arylation

Abstract

The modular design of polyphosphines, diversely functionalized for facile immobilization on virtually any kind of support, is reported. Previously unobserved ABCD (31)P NMR spin-spin systems evidence the control exercised on the polyphosphines conformation. We illustrate the catalytic performance at low Pd loading of the recyclable immobilized polyphosphines in C-C bond formation reactions.

Highly Functionalized Ferrocenes

“…Accordingly, the existence of a strong through‐space spin‐spin coupling ( TS J PP = 64.3 Hz and 61.0 Hz, respectively) between internal heteroannular AA' pairs of P‐atoms is due to the overlapping of their lone pairs. Such spin couplings attest for the ligand conformation in solution . Tetraphosphine 7 was modified to give the functionalized polyphosphines 8–11 (Figure ).…”

“…The monofunctionalized analogues 12–14 and the vinyl difunctionalized tetraphosphine 15 (Figure ) were also synthesized following the method of assembling adequately substituted Cp rings . One aim was to increase the flexibility of the anchoring upon immobilization ( 12–14 , being not cross‐linking species) or to generate a short cross‐linker tetraphosphine ( 15 ).…”

“…Because of their efficiency in Pd‐catalyzed C–C and C–O bond formation, ferrocenyl triphosphines were extended to specimens “ready for immobilization”, as we achieved for a number of ferrocenyl tetraphosphines (Figure ). The triphosphines 30–35 (Figure ) were obtained by the assembly of substituted cyclopentadienyllithium at FeCl 2 , using the same kind of precursors as E (Figure ), together with (phosphino)cyclopentadienyllithium salts , …”

Highly Functionalized Brønsted Acidic/Lewis Basic Hybrid Ferrocene Ligands: Synthesis and Coordination Chemistry

“…These can bear various functional and structuring spectator substituents, and their preparation clearly involves synthetic difficulties arising mainly from the need of multiple functionalization and functional group compatibility. In this context, the Hierso group designed highly functionalized hybrid ligands and polyphosphanes (1,1′,3,3‐tetrafunctionalized) using dialkylated 1,1′‐ tert ‐butylferrocene as a scaffold (Scheme b), and cousin compounds with geminally dimethylated substituents . These compounds were used as ligands promoting metal‐catalysed C–C and C–X bond formation (X = O, S, etc.)…”

Graphical Abstract: ChemPlusChem 10/2015

“…At approximately the same time, the authors of this Full Paper independently submittedarelated Communication to Chemical Communications, [1] in which identical compounds were described. The overlapping timeframe resulted from delays caused by apatentapplication.T he corresponding author did not mention this Communication to the editorialoffice upon submission of the Full Paper and neglected to crossreference thesearticles, therefore he would like to sincerelyapologize to the editorial staff and readers of ChemPlusChem for this unintentional mistake.…”