Diphenylphosphinyl group

Deamination reactions of (2-amino-l,l-dimethyl)ethyldiphenylphosphine oxide (57) result in the formation of three products, in each of which the diphenylphosphinyl group has migrated to the primary carbon of the starting material. These reactions are unusual examples of non-assisted migration of a phosphinyl group. 

The benzannulated analog 115 was likewise synthesized from 114 (Scheme 20.24) [56, 63], However, unlike 109, thermolysis of 115 resulted in its slow decomposition without the formation of the cycloaromatized adduct 116. The lack of propensity for 115 to undergo the Myers-Saito cyclization reaction was attributed to unfavorable steric interactions between the diphenylphosphinyl group and the aryl ring of the benzannulated enyne-allene system, causing the allenic moiety to be rotated out of the plane defined by the aryl ring and preventing the cyclization reaction. 

The enyne-allenylphosphine oxides 120 and the benzannulated and naphthannu-lated analogs 121 and 122 having the diphenylphosphinyl group at the allenic terminus were readily prepared from the corresponding enediynyl propargylic alcohols 117,118 and 119 (Scheme 20.25) [64]. Without the unfavorable steric interactions, these conjugated derivatives smoothly underwent the Myers-Saito cyclization reaction. 

Anodic oxidation of the carbamates 17 and 23 in methanol, followed by reaction with chlorodiphenylphosphine affords the a-diphenylphosphinylcarbamates 20 and 25, from which the readily generated carbanions react with aldehydes to give the 4-phosphinyl-2-oxazolidinones 21 and 26. The removal of the diphenylphosphinyl group by a mild thermal treatment provides a route to the 2(3//)-oxazolones 22 and 27 (Fig. 5.6). ... 

Changing the ligand structure by substituting two dibenzophosphole groups for two diphenylphosphinyl groups results in a variation of the prevailing chirality in butenes but not in styrene 48). 

A stereoselective synthesis of ( )-ephedrine and ( )-methylephedrine has been described (318). The method utilizes a carbanion, in which the negative charge is located a to the nitrogen, formed by deprotonation of 1. Subsequent reaction with benzaldehyde yields the 2-oxazolidone 2, and thermal removal of the diphenylphosphinyl group gives the 2-oxazolone 3. Hydrogenation of 3 proceeds with perfect stereoselectivity to yield the erythro isomer 4, which is easily converted to ( )-ephedrine or ( )-W-methylephedrine. 

Similarly, starting from d-terr-butyl-l-ethynylcyclohexanol with either an axial or an equatorial hydroxy group, phosphine oxides 2 are obtained in which the diphenylphosphinyl group is homo-axial or homo-equatorial, respectively (see also Table 2)25. 

The Darzens reaction of the oxazoline 360 with a series of aldimines has been shown to form aziridine 362 in good yields and with high diastereoselectivity <2005X3251>. Deprotonation of the aziridine to form the aziridinyl anion and subsequent reaction with an electrophile provide the highly substituted aziridines 363 in moderate yields. The diphenylphosphinyl group on the nitrogen provides optimal yields in the lithiation reaction (Scheme 94). 

A chiral bisphosphine containing two ferrocene moleeules has been prepared using Ugi s lithiation as a key step (Scheme 2-9) [20]. Thus, the diphenylphosphinyl group is introduced at the ferrocenylmethyl position of the iodide obtained from lithiated ferrocene 2. Oxidative coupling of the iodoferrocene followed by reduction of the phosphine oxide gives the bisferrocene-bisphosphine 15. The bisphosphine is unique in that a tra j-chelate is formed on its coordination to a metal. 

These migrations involve a 1,2-shift of the diphenylphosphinyl group from a tertiary to a primary carbon, but in a further paper migrations from a tertiary carbon to a tertiary carbonium centre, in the oxides (41c, d), have been described (Scheme 7). Evidence for the intermediacy of the ion... 

Davidson and Warren have used the diphenylphosphinyl group as an activating group in synthesis of 1,3-dienes from an alkyl halide and two carbonyl compounds as outlined in equation I. 

The reaction of ynamines of type 2.217, in which R is a diphenylphosphinyl group, their sulfur or seleno analog ((C6H5)2P(X), X = O, S, Se), corresponds to that of reaction (2-85). Again, the triazoles are in equilibrium with the diazoamidines (Himbert and Regitz, 1974). A large number of )ff-metalyl-ynamines show the same reaction pattern. The metals are trialkylated or triphenylated Si, Ge, and Sn (Himbert et al., 1976). 

Compounds 1, which bear in X an electrofugical leaving group, such as trialkylsilyl or diphenylphosphinyl, are of high value for the synthesis of stereochemically homogeneous 1,3-dienes via stereospecific anti or urn elimination. 

Amination of Group 1,2, 11 and 12 organometaiiic reagents Colvin and coworkers have reported the amination of phenyl and hexylmagnesium bromides with 0-(diphenylphosphinyl)hydroxylamine 4a (equation 22) . 

A complication in aziridination is that metal carbenoids can react directly with some imines to yield aziridines. Fortunately, imines bearing electron-withdrawing groups are less reactive to carbenoids and more reactive to ylides than electron-rich imines. Thus, N-tosyl, N-diphenylphosphinyl and N-[-(tri-methylsilyl)ethansulfonyl] imines (-(trimethylsilyl)ethansulfonyl = SES) were all suitable substrates using dimethylsulfide and Rh2(OAc)4, with no background reaction detected [77, 78]. Phenyldiazomethane, N,N-diethyl diazoacetamide and ethyl diazoacetate could be used as the diazo component, although the latter two required temperatures of 60 °C to decompose. 

Recently, Majoral et al. described the synthesis of a third-generation phosphorus-containing dendrimer possessing 24 chiral iminophosphine end groups derived from (2S)-2-amino-l-(diphenylphosphinyl)-3-methylbutane (Fig. 11) [32]. The dendritic catalyst was tested in allylic substitution reactions, using rac-(.E)-diphenyl-2-propenyl acetate or pivalate as substrates. The observed enantioselectivities were good to excellent (max. 95% ee) in all reactions. After completion of the catalytic reaction, the catalyst could be reused at least twice after precipitation and filtration. A slight decrease... 

Asymmetric hydrogenation. Simpler ligands of this type, but still based on a r-diphenylphosphinyl-2-(diphenylphosphino)methylpyrrolidine (PPPM), were first eported in 1976 (8, 57-59) to be useful for asymmetric hydrogenation of 2-ace-umidoacrylic acids. Since then a para-methoxy group on the phenyl groups has... 

In 1995, the author s group also measured CIDEP spectra for the photodissociation of triphenyl-phosphine (PhsP) in some fluid homogeneous solutions at 293 K [7], Fig. 10-11 shows a typical spectrum among them. In this figure, absorptive signals due to the 2-hydroxy-2-propyl and diphenylphosphinyl radicals ((CH3) 2C OH and Ph2P ) were observed at a delay time of 0.25 ps after laser excitation. The latter radical is produced by Reaction (10-20e), but the former one by the secondary reaction from the phenyl radical generated from Reaction (10-20e) as follows ... 

The enantioselective synthesis of optically active secondary amines via asymmetric reduction of prochiral ketimines was studied by screening various chiral hydrides. In this case, K-glucoride gave only disappointing results and was inferior to other reagents. Better results were obtained in the asymmetric reduction of prochiral Af-diphenylphosphinylimines to chiral N-(diphenylphosphinyl)amines (eq 1), which can then be readily converted into optically active primary amines. For this reaction the stereochemical course depends dramatically on the relative bulkiness of the groups R and R. The reaction conditions for reduction of C=N double bonds are the same as used for ketones, but the high reactivity of diphenylphosphinylimines dramatically reduces the reaction time. 

The attachment of the strongly electronegative phosphinyl (P—O) group to an imine, usually via reaction of an oxime with a chlorophosphine, also gives highly electrophilic imines which are reduced by NaBFWTHF and various modified borohydride and LAH derivatives " under mild conditions. The product A-phosphinylamines are protected forms of primary amines since removal of the phosphorus substituent is accomplished under mild acidic conditions. Entries 12 and 13 (Table 16) present representative reductions and illustrate (entry 13) that highly diastereoselective reductions of cyclic systems to axial amine derivatives are accomplished with LiBHBu s. Enantioselective reductions of A-diphenylphosphinyl imines to optically active amine derivatives have also been reported (Chapter 1,7, this volume). ... 

Hydroxylamines usually react with acid chlorides to give mixtures of N-, O- and poly-acylated products. In contrast reaction of tris(trimethylsilyl)hydroxylamine (65) with aliphatic acid chlorides leads selectively under /V-monoacylation to the corresponding hydroxamic acids (66 equation 26). While di-phenylphosphinic chloride (68) is attacked by the oxygen of hydroxylamine to yield 0-(diphenylphos-phinyl)hydroxylamine (67 Scheme 13), A -(diphenylphosphinyl)hydroxylamine (69) can be obtained by treatment of diphenylphosphinic chloride with 0-trimethylsilylhydroxylamine followed by removal of the silyl blocking group (Scheme 13). 0-Acylation of arylhydroxylamines can be achieved with acyl cyanides. ... 

Diphenylphosphinyl chlorides and simple ylides yield 1-diphenylphosphinylalkylidenephosphoranes in a transylidation reaction the introduction of the thiophosphinyl group may be carried out analogously (equation 32). Synthesis of diethoxy- and diphenoxy-phosphinomethylenetriphenylphosphoranes may be achieved with the corresponding phosphoro chloridates (equation 33). 

Petrov, E.S., Tsvetkov, E.N., Mesyats, S.R, and Shatenshtein, A.L, Equilibrium CH-acidity of organophosphorus compounds. Part 4. Acidifying effects of diphenylphosphinyl, carbethoxy, nitrile, and phenyl groups, Izv. Akad. Nauk SSSR, Ser. Khim., 782, 1976 Bull. Acad. Sci. USSR, Div. Chem. Sci. (Engl. Transl.), 762, 1976. 

Orthoesters annulate aminomethyl and amino groups to form a fused pyrimidine ring [2159]. Two amino groups in peri positions form a similar ring when treated with benzoic acid and. -diphenylphosphinyl-iV -methylpiperazine [3286] (see also Chapter 76, Section 1.1.A). 1,8-Naphthalenediamine is converted into perimidine by heating with 2-acylindanedione and 4-toluenesulphonic acid [2354]. Formic acid similarly cyclizes 4,5-quinolinediamine or the isomeric isoquinolinediamine in about 89VO yield [3338]. 

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