Bis phosphonite

One of the drawbacks of the use of bisphosphines is the elaborate syntheses necessary for their preparation. Many efforts have been directed towards the development of bis-phosphonites and bis-phosphites. However, surprisingly mono-dentate phosphinates, phosphates and phosphoramidates recently emerged as effective alternatives for bidentate phosphines (Fig. 3.29). This constitutes an important breakthrough in this area as these can be synthesized in one or two steps, and the cost of these ligands is an order of magnitude lower Monophos can be made in a single step from BINOL and HMPT. 

The pyrophosphite bridged lantem-t3q)e platinum(II) complexes are known to give strong emissions. Analogous complexes with methylene-bis(phosphonite) as a bridging ligand are also emitters. Their electronic structures and associated reactivities have been extensively studied and are summarized in a review article (8). Some further information... 

The fully saturated systems (1,3-diphosphinanes) have also received attention. A double Arbuzov reaction on the bis-phosphonite (135) forms the cyclic diphosphinate (136), which can be reduced to the diphosphine (137) (Scheme 25) <89PS(4l)ll3>. The synthesis and stereochemistry of the 1,3-diphenyl analogue (138) have also been reported <89PS(44)235>. 

For leading review of novel 1,3-diphosphite, phosphine-phosphite, bis-phosphonite ligands, see. Ref (6) and (10). 

Two preparations of diesters of phosphonous acid have been reported, - One of these, which claims to be the first preparation of these derivatives, involves the reaction of ammonium hypophosphite with triaikylsilylamines to give bis(trialkylsilyl) esters (127) in excellent yield. These compounds are extremely reactive, e.g. they are spontaneously inflammable in air. Dialkyl phosphonites (128) have also been prepared by the reduction of... 

Hydrolysis products With an excess of water by weight, QL form 2-diisopropylaminoethanol, ethanol, and methyl phosphorous acid. With traces of water or other proton donors QL will produce diethylmethyl phosphonite and 0,0 -bis-(2-diisopropylaminoethyl) methylphosphonite. Diethylmethyl phosphonite has a boiling point of 120°C and a vapor pressure of 11 mmHg at 20°C and is highly flammable. 

Bis(acrylonitrile)nickel(0), 2312 l,2-Bis(dichlorophosphino)ethane, 0797 Bis(trimethylsilyl) phosphonite, 2611 Bromodimethylborane, 0887 Calcium silicide, 3943 Cerium trisulfide, 3967 Chromium(II) acetate, 1493 Chromium(II) oxide, 4241 Cobalt(III) nitride, 4214 Cobalt(II) sulfide, 4218 Dicobalt boride, 0128 Dimethyl ethanephosphonite, 1732 Europium(II) sulfide, 4293 2-Furaldehyde, 1836 Indium(II) oxide, 4641... 

A convenient procedure for preparing dialkylphosphinic acids 62 involves addition of H-phosphinic acids and esters to conjugated double bonds via the silyl 87-89 or metal phos-phonite 61,[90 94] as illustrated in Scheme 21. The silyl phosphonite intermediates 61 (M = TMS) are typically formed either from phosphinic acids or esters using chlorotri-methylsilane or bis(trimethylsilyl)acetamide. The metal phosphonite intermediates 61 (Y = Li, Na, etc.) are prepared by deprotonation of the acids with a base such as sodium hydride, sodium methoxide, or lithium diisopropylamide. The conjugated double bonds are typically acrylic acids and esters substituted in the a-position with the appropriate amino acid side chain. After appropriate protecting group manipulations, additional amino acids... 

As illustrated in Fig. 6, imines serve as important intermediates for a number of solid-phase syntheses. Additional uses for these versatile intermediates are described in Fig. 9. Resin-bound thioketene acetals have been shown to condense with imines to provide, after reductive cleavage, a route to substituted aminoalcohols 6 [45], Aminophosphinic acids 7 were prepared by allowing bis(trimethylsilyl)phosphonite to react with resin-bound imines [46],... 

Regan and co-workers protocol for the synthesis of y-keto phosphinic acids by 1,4-addition of bis(trimethylsilyl)phosphonite (BTSP, 64) to a,p-unsaturated ketones avoids the isolation of pyrophoric BTSP 64 by generating it in situ. This procedure may be modified to synthesize disubstituted phosphinic acids by addition of a second a,p-unsaturated ketone.133 a,f)-Unsaturated esters are also suitable reactants.134 The products are isolated most conveniently as their adamantanammonium salts.133... 

Attack on Unsaturated Carbon.- A versatile route to phosphinic acids (15) is the 1,4-addition of bis(trimethylsilyl) phosphonite (16) to a,p-unsaturated esters.The pyrophoric (16) was prepared in s/fu from triethylammonium phosphinate silylation and 1,4-addition can be repeated to give (17), or performed in one step if symmetrical phosphinic acids (17) are wanted. Tervalent phosphorus acid esters (18) react with dialkyl acetylenedicarboxylates in the presence of carbon dioxide to give 1,2-oxa-phospholenes (19) these reacted further with an excess of the phosphorus reagent to give different ylids, (20) or (21), dependant on the number of methoxy groups in (18). 

Trimethylsilyl esters of dialkyIphosphinic acids have been prepared from alkyl halides and bis(trimethylsilyl) phosphonite in the presence of Me SiCl-Et N final ethanolysis gave the free... 

Chiral cationic Rh catalysts for the hydrogenation of prochiral C-C double bonds require the use of BARF or related anions even with potentially CO2-S0IU-ble ligands such as Et-DuPHOS (DuPHOS l,2-bis(2,5-dialkylphospholano)-benzene) [70] or a perfluoroalkyl-substituted aryl phosphonite [19]. The ligand... 

A significant development that has received widespread attention is the synthesis of new mono-and bis-substituted chiral phosphinite, phosphonite, and phosphite ligands. The standard protocol for their syntheses is based on that illustrated in Figure 5. For example, the synthesis of the chiral diphosphinite (182)409 is shown in Equation (45), this basic procedure working extremely well for other chiral diphosphinites such as (183) and (184).410,411... 

Allyl phosphorodichloridite. 1169 Bis(trimethyIsilyl) phosphonite, 2611 0-0-tert-Butyl diphenyl monoperoxophosphate, 3712 0-0-tert-Butyl di(4-tolyl) monoperoxophosphate, 3763 Diallyl phosphite (Di-2-propenyl phosphonite), 2456 Dibenzyl phosphite, 3658 Dibenzyl phosphorochloridate, 3650 Di(( -( -teri-butyl) ethyl diperoxophosphate, 3374 Dibutyl hydrogen phosphite, 3086 Diethyl ethanephosphonite, 2572 Diethyl 4-nitrophenyl phosphate, 3329 Diethyl 4-nitrophenyl thionophosphate, 3328 Diethyl phosphite, 1733... 

Bis(dichlorophosplnno)cthane, 0797 Bis(trimethylsilyl) phosphonite, 2611 Bromodimethylborane, 0887 Calcium silicide, 3943... 

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