Phosphinic chlorides

The rate of solvolysis of the phosphinic chlorides (83a, b) in trifluoro-acetic acid and aqueous acetone (the composition of the latter solvent being chosen such that the rate of S nI solvolysis of Bu Cl was the same in both) have been examined to assess the possible operation of an 5 n1(P) ionization mechanism. In the more nucleophilic aqueous acetone solvent,... 

The reaction between 2-adamantyl halides and PCl /AlBr yields a mixture of di-2-adamantylphosphinic chloride and bromide together with (1-adamanyl)(2-adamantyl)phosphinic chloride 1-adamantyl halides are already known to afford only 1-adamantylphosphonic acid derivatives. 

Reactions of the hydroxy peptides with selected phosphine chlorides in the presence of a base and catalytic amounts of DMAP resulted the corresponding phosphinites, which readily form Pd and Pt complexes (Scheme 2). 

Cyclization of 1-carboxypentyl pipecolinate with bis(2-oxo-3-oxazolidinyl)phosphinic chloride in DMF in the presence of Htinig s base afforded 3-butylperhydropyrido[2,l-f][l,4]oxazine-l,4-dione <1996DEP4440193>. Cyclization of methyl 4-(alr-3,5-H-2-oxomorpholin-5-yl)butyrate in boiling toluene provided ar-4,9a-//-4-phenylper-hydropyrido[2,l-f][l,4]oxazine-3,6-dione <1995H(41)1931, 2000T233>. 

Larger chalcogen-phosphorus heterocycles, although less common in the literature, are accessible via a variety of synthetic routes.2,83,84 For example, the cyclic trimer (SPR)3 (R = 2,4,6-tri-tert-butylphenyl) contains a puckered six-membered P3S3 ring and is produced in the reaction of a phosphinic chloride with lithium sulfide (Equation 73).98 Additionally (R P)3Se5 (R = 2,4-di-tert-butyl-6-wopropoxyphenyl), synthesised from the oxidation of a primary phosphine with three equivalents of elemental selenium (Equation 74), has... 

Acetals have been used in the presence of Lewis acids, particularly zinc chloride and ferric chloride, for the addition of phosphorus-halogen species to prepare 1-alkoxyphosphonic dichlorides and dialkyl 1-alkoxyphosphonates (from phosphorus trichloride and dialkyl phosphinous chlorides, respectively).143-145 It should be noted that good yields of these types of products have also been reported in the absence of catalysts.146 147 Other types of substrates have also been used in these types of processes. These include acylals,148 amidals,149 orthoformates,150 and orthoacetates.151... 

According to the latter approach, reducing sugars 128 were reacted with triethylammonium dimethyl boranophosphate in the presence of bis(2-oxo-3-oxazolidinyl)phosphinic chloride as condensing reagent, 3-nitro- 1,2,4-triazole as nucleophilic catalyst and A,A-diisopropyl-A-ethyl-amine to provide boranophosphate triester derivatives 129 as anomeric... 

Carbon tetrachloride-organo-phosphine, chlorides from alcohols with, 54, 63 CARBONYL CYANIDE, 51, 70 Carbonyl cyanide, with alcohols, 51, 72... 

FIGURE 8.21 Proposed mechanism for the BOP-Cl-mediated reaction of a carboxylate anion with a methylamino group. Formation of a mixed anhydride is followed by aminolysis that is facilitated by anchimeric assistance provided by the oxygen atom of the ring carbonyl.101 (van der Auwera Anteunis, 1987). BOP-C1 = fcw(2-oxo-3-oxazolidino)phosphinic chloride. 

C van der Auwera, MJO Anteunis. N,N-bis(2-oxo-3-oxazolidinyl) phosphinic chloride (BOP-C1) a superb reagent for coupling at and with iminoacid residues. Int J Pept Prot Res 29, 574, 1987. 

A similar mechanism to the previous ones was proposed by Deng, Shi and coworkers for the bis(2-oxo-3-oxazolidinyl)phosphinic chloride (BOP-Cl, 269) catalytic Beckmann rearrangement (equation 82). Addition of the Lewis acid zinc chloride improved the catalyst performance and amides were synthesized in excellent yields (92-99%). 

Peroxyphosphonate can be prepared by a similar reaction in the presence of pyridine instead of the sodium salt of the hydroperoxide. Peroxyphosphonates 72 are generally synthesized by the condensation of the corresponding phosphinic chloride with the sodinm salt of terf-butyl hydroperoxidate in a neutral solvent in the presence of sodinm snlfate, or alternatively, by the reaction of terf-butyl hydroperoxide with phosphinic chloride in the presence of pyridine . 

The activated phosphorus reagents 269 and 270 are conventionally prepared by the reaction of 2(3//)-oxazolone with the corresponding phosphorus chlorides in the presence of triethylamine. The phosphorus chlorides employed include phosphoryl chloride, thiophosphoryl chloride, mono- and dichlorophosphates, and phosphinic chloride (Fig. 5.66). 

Cyclization was carried out at 1 mM peptide concentration in DMF with bis(2-oxo-3-ox-azolidinyl)phosphinic chloride in the presence of TEA. The cyclic product was isolated by RP-HPLC yield 24%. Deprotection was carried out by hydrogenolysis in MeOH over 10% Pd/C with ammonium formate. 115 The product was isolated by RP-HPLC yield 78%. 

Method D Elimination of HCI from Cyclic Phosphine Chlorides... 

An entirely different method for the preparation of X -phosphorins utilizes phosphine chlorides 36 or 40. Treatment with bases leads to HCI elimination and to the formation of the X -phosphorins 37 and 41, respectively. The phosphine chlorides can be prepared from cyclic phosphinic acids 34 by reduction with diphenylsilane to the cyclic phosphines 35 followed by chlorination with phosgene. Alternatively,... 

To the resulting red-brown suspension, a solution of bis(3,5-dimethylphenyl)-phosphine chloride (3, 21.0 g, 76.0 mmol) in 100 mL THF was added at —78°C under a N2 atmosphere. The reaction mixture was allowed to warm to room temperature and stirred at this temperature overnight. 

Carbon tetrachloride-organo-phosphine, chlorides from... 

A large variety of phosphorus derivatives can also be used. R2PCI can be used to give a quaternary phosphonium salt directly. Cyclic phosphinous chlorides are also effective and some examples have already been mentioned. Also, the different reactivities of chloro and bromo phosphines, the former giving largely 2-phosphoIene and the latter 3-phos-pholene derivatives, should be noted. 

It was later found that dialkyl(dialkylamino) phosphites (phosphoramidites, (RO)2PNR2 [114]), which are stable towards air and water and can be stored for longer, can readily be converted into the phosphinic chlorides (RO)2PCl by treatment with dimethylaniline hydrochloride, or into the corresponding tetrazolides by treatment with tetrazole. Tetrazolides (RO)2P-(l-tetrazolyl) had proven excellent reagents for the phosphorylation of nucleosides [113], and the treatment of phosphoramidites with alcohols in the presence of tetrazole was found to be a satisfactory method for the rapid preparation of trialkyl phosphites [115,116]. 

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