Architecture and synthesis of P , N-heterocyclic phosphine ligands

Abstract

Diverse P,N-phosphine ligands reported to date have performed exceptionally well as auxiliary ligands in organometallic catalysis. Phosphines bearing 2-pyridyl moieties prominently feature in literature as compared to phosphines with five-membered N-heterocycles. This discussion seeks to paint a broad picture and consolidate different synthetic protocols and techniques for N-heterocyclic phosphine motifs. The introduction provides an account of P,N-phosphine ligands, and their structural and coordination benefits from combining heteroatoms with different basicity in one ligand. The body discusses the synthetic protocols which focus on P-C, P-N-bond formation, substrate and nucleophile types and different N-heterocycle construction strategies. Selected references are given in relation to the applications of the ligands.

Keywords: P,N-heterocyclic phosphines; ligand synthesis.

Scheme 1

Synthesis of pyridylphosphine ligands.

Figure 1

Pyridylphosphine ligands.

Scheme 2

Synthesis of piperidyl- and oxazinylphosphine ligands.

Scheme 3

Synthesis of linear multi-chelate pyridylphosphine ligands.

Scheme 4

Synthesis of chiral acetal pyridylphosphine ligands.

Scheme 5

Synthesis of diphenylphosphine-substituted triazine ligands.

Scheme 6

Synthesis of (pyridine-2-ylmethyl)phosphine ligands.

Scheme 7

Synthesis of diphosphine pyrrole ligands.

Scheme 8

Synthesis of 4,5-diazafluorenylphosphine ligands.

Scheme 9

Synthesis of thioether-containing pyridyldiphosphine ligands starting from ethylene sulfide and diphenylphosphine.

Scheme 10

Synthesis of monoterpene-derived phosphine pyridine ligands.

Scheme 11

Synthesis of N-phenylphosphine-substituted imidazole ligands.

Scheme 12

Synthesis of triazol-4-ylphosphine ligands.

Scheme 13

Synthesis of phosphanyltriazolopyridines and product selectivity depending on the substituents’ effects.

Scheme 14

Synthesis of PTA-phosphine ligands.

Scheme 15

Synthesis of isomeric phosphine dipyrazole ligands by varying the reaction temperature.

Scheme 16

Synthesis of N-tethered phosphine imidazolium ligands (route A) and diphosphine imidazolium ligands (route B).

Scheme 17

Synthesis of {1-[2-(pyridin-2-yl)- (R = CH) and {1-[2-(pyrazin-2-yl)quinazolin-4-yl]naphthalen-2-yl} (R = N) diphenylphosphine ligands 95.

Scheme 18

Synthesis of oxazolylindolylphosphine ligands 102.

Scheme 19

Synthesis of pyrrolylphosphine ligands.

Scheme 20

Synthesis of phosphine guanidinium ligands.

Scheme 21

Synthesis of a polydentate aminophosphine ligand.

Scheme 22

Synthesis of quinolylphosphine ligands.

Scheme 23

Synthesis of N-(triazolylmethyl)phosphanamine ligands.

Figure 2

Triazolylphosphanamine ligands synthesized by Wassenaar’s method [22].

Scheme 24

Synthesis of oxazaphosphorines.

Scheme 25

Synthesis of paracyclophane pyridylphosphine ligands.

Scheme 26

Synthesis of triazolylphosphine ligands.

Figure 3

Click-phosphine ligands.

Scheme 27

Ferrocenyl pyridylphosphine imine ligands.

Scheme 28

Synthesis of phosphinooxazolines (PHOX).

Scheme 29

Synthesis of ferrocenylphosphine oxazoles.