Convenient Methods for the Synthesis of a Library of Hemilabile Phosphines

Abstract

A series of novel functionalized phosphines of hemilabile character, R 2 P(CH 2 ) n Z, have been prepared from diarylphosphines using several synthetic methodologies. The synthetic methods include the alkylation of lithium diarylphosphide or diarylphosphino-borane adducts with functionalized halogenoalkanes, X-(CH 2 ) n -Z, and the photochemical hydrophosphination of suitable functionalized allyl or vinyl derivatives, CH 2 =CH-Z or CH 2 =CH-CH 2 -Z, using white light. A range of R 2 PH (R = C 6 H 5 -CH 2 , p-CH 3 O-C 6 H 4 , p-CH 3 -C 6 H 4 , o-CH 3 -C 6 H 4 , C 6 H 5 , p-CF 3 -C 6 H 4 ) has been used in order to tune the electronic density on the P donor atom. The coordination ability of the hemilabile fragment was modified by selection of the donor group (Z = OMe, OEt, OnBu, NMe 2 ) or the length of the flexible carbon chain (n = 2, 3). Hemilabile fluorinated allyl phosphines, R 2 PCH 2 CH=CH 2 (R = p-F-C 6 H 4 , C 6 F 5 ), have been prepared from diarylchlorophosphines and allymagnesiun bromide.

Bis(pentafluorophenyl)phosphinous acid in the synthesis of P,P-bis(pentafluorophenyl)phosphorylalkanones and -alkanediones

“…** According to the recent data, 24 bromophosphine 10 can be easily synthesized in one step by the reaction of C 6 F 5 MgBr with PCl 3 , whereas a two step process remains the only method for the synthesis of chlorophosphine 11, reliably leading to the indi vidual product: C 6 F 5 MgX  (C 6 F 5 ) 2 PNRR´  11 (see, for example, Ref. 18). IR spectra were recorded on a Bruker Tensor 37 Four ier transform spectrometer (resolution 2 cm -1 ) in the region of 400-4000 cm -1 .…”

“…The signals for the nuclei of 13 C (see Ref. 18) and 19 F atoms 19 were assigned based on the data published earlier. In the 13 C{ 1 H} NMR spectrum of phosphoryl ketone 2, the sig nal for the carbonyl carbon atom was found as a doublet with a spin spin coupling constant 3 J C,P = 12.…”

Diphenyl(2-propoxyethyl)phosphine

“…Due to this feature, the (ether) oxygen atom can easily be displaced by an incoming substrate. In addition, the oxygen function, which may be regarded as an intramolecular solvent, is able to stabilize a transition-metal fragment after substrate dissociation, and therefore, decomposition is suppressed [4][5][6][7][8][9]. Thus, ether phosphines are capable of making available and protecting vacant coordination sites and lead to an improvement in both catalytic and stoichiometric reactions [5][6][7][8][9] The strength of the metal oxygen bond in (ether phosphine)ruthenium complexes depends on the O nucleophilicity of the ether moiety, the ring size of the cyclic ether, the number and position of the oxygen atoms in the ring, and the basicity at the metal.…”

“…In recent years, there has been a considerable interest in the design and use of so-called hemilabile ligands [1][2][3][4][5]. They contain a soft donor (e.g., phosphorus) closely coordinated to the transition metal with a hard donor (e.g., oxygen) forming only a weak contact to the metal center.…”

Mechanistic Studies on the Catalytic Oxidative Amination of Alkenes by Rhodium(I) Complexes with Hemilabile Phosphines

“…CDCl3, CD2Cl2, THF-d8 (Euriso-top) were dried using activated molecular sieves. The functionalized hemilabile phosphine, Ph2P(CH2)3OEt, 17 and catalyst precursors 1-6 15 were prepared following published methods (see supporting information). [b] Selec.…”