Triphenyl phosphonium iodide

The present preparation illustrates a general and convenient method for the fnms-iodopropenylation of an alkyl halide.4 The iodopropenyl-ated material is not usually stable but is a useful synthetic intermediate. For example, it forms a stable crystalline triphenylphosphonium salt for use in the Wittig reaction, and under Kornblum reaction conditions (DMS0-NaHC03, 130°, 3 minutes) it gives an (E)-a,/9-unsaturated aldehyde.4 In addition to the phosphonium salt described in Note 15, the following have been prepared (4-p-methoxyphenyl-2-butenyl)-triphenylphosphonium iodide [Phosphonium, [4-(4-methoxyphenyl)-2-butenyl]triphenyl-, iodide], m.p. 123-127° (2-octenyl)triphenyl-phosphonium iodide [Phosphonium, 2-octenyltriphenyl-, iodide], m.p. 98° and (2-octadecenyl)triphenylphosphonium iodide [Phosphonium, 2-octadecenyltriphenyl-, iodide], m.p. 50°. 

Phenylurethanes. 58, 10 Phosgene, 57, 46 Phosphine, diphenyl-, 56, 45 Phosphine-nickcl catalyst, 58, 129 PHOSPHINE-NICKEL CATALYZED COMPLEX CROSS-COUPLING OF GRIG-NARD REAGENTS WITH ARYL AND ALKENYL HALIDES, 58, 127 Phosphine, phenyl-, bis(3-dimethylamino-piopyl)-, 55, 128 Phosphine, triphenyl-, 56, 81 Phosphonium, 14-(4-methoxyphenyl)-2-butenyl] triphenyl-, iodide, 56, 81 Phosphonium, 2-octadecenyltriphenyl-, iodide, 56, 81... 

Phosphine, diphenyl- [829-85-6], 45 Phosphine, triphenyl- [603-35-0], 81 Phosphonium, [4- 4-methoxyphenyl)-2-butenyl) triphenyl-, iodide [57620-96-91,81... 

This material may be converted directly to a phosphonium salt 1.40 g. (0.0054 mole) of the crude iodide is dissolved in 20 ml. of benzene, and 1.42 g, (0.0054 mole) of triphenylphosphine [Phosphine, triphenyl-] is added. On standing, 2.5 g. (77%) of the triphenylphosphonium salt precipitates as a colorless 1 1 complex with benzene, m.p. 135-137°. Recrystallization from methanol-benzene raises the melting point to 140-142°. Analysis calculated for C28H29PI CeH6 C, 68.23 H, 5.39. Found C, 68.15 H, 5.28. 

Iodoallenes are prepared from propargyl alcohols by means of phosphonium iodide produced in situ from triphenyl phosphite and methyl iodide. In addition, small amounts of the isomeric iodoacetylenes are formed in this process. 

Hydroboration.1 The usual hydroboration reagents, BH3THF and BH3-S(CH3)2, are sensitive to oxygen and moisture and require special handling. 1 he complexes of BH3 and phosphorus compounds are generally stable, but much less reactive. The complex of BH3 and triphenylphosphine, m.p. 189°, can be used for hydroboration if activated by addition of methyl iodide (to form a phosphonium iodide) or sulfur (to form a triphenylphosphine sulfoxide). The complex of borane and triphenyl phosphite does not require activation and hydroborates alkenes in a reasonable time in refluxing DME or THF. Trialkyl phosphite complexes are not useful. 

Phenylthiovinyl(triphenyl)phosphonium iodide. Rhodium(II) carboxylates. 

One of the most used resins in solid-phase combinatorial organic synthesis, which has found a myriad of applications, is the Merrifield resin (17).61 This resin is also the building block for a tremendous amount of novel resins being developed in combinatorial chemistry with applications in both solid-phase as well as solid-phase-assisted solution-phase combinatorial chemistry. A recent, useful, and novel example is the report of its being employed as a triphenylphosphine scavenging resin.76 During the conversion of azidomethylbenzene (51) into benzylamine, excess triphenyl-phosphine is allowed to react with Merrifield resin (17) in the presence of sodium iodide in acetone. A phosphonium-substituted resin (52) is thus formed. Upon simple filtration, pure benzylamine is isolated as shown in Fig. 22. 

The next reaction in this sequence is an Appel reaction, which transforms an alcohol to an alkyl iodide. The simplified mechanism is depicted in the margin. The initial step of this reaction is the nucleophilic attack of triphenyl phosphine to iodine with formation of an iodine triphenyl phosphonium cation. The positive charge increases the oxophilicity of phosphorus, which is attacked in the next step by an alcohol. After elimination of hydrogen iodide, the resulting alkoxy triphenyl phosphonium cation is attacked by an iodide anion in an SN2-type reaction. Therefore, the reaction of chiral alcohols typically proceeds with inversion of configuration, although other behavior is also reported. The product of the Appel reaction is alkyl iodide 37 and triphenyl phosphine oxide is formed as byproduct. ... 

ALKENES Calcium amalgam. N,N-Dimethylformamide dimethyl acetal. N,N-Methylphenylaminotriphenyl-phosphonium iodide. N,N,N, NrTetra-methyldiamidophosphorochloridate. Titanium(O). p-Toluenesulfonylhydra-zine. Tii-n-butyltin hydride. Triphenyl-phosphine-Diethyl azodicaiboxylatc. Trityl tetrafluoroborate. 

The synthesis of a novel cyclopropyl analog of arachidonic acid [7] via a convergent synthesis that employed methyl (lR,25)-2-formylcyclopropane-carboxylate in conjunction with the ylide from (3Z,6Z)-pentadeca-3,6-dienyl(triphenyl)-phosphonium iodide was reported (62). A new approach to cyclopropene fatty acids has been developed for the synthesis of methyl sterculate [8] and methyl 2-hydroxy-sterculate this involves the 1,2-deiodination of 1,2-diiodocyclopropanes with butyllithium at low temperature (63). The synthesis of deuterated cyclopropene fatty esters structurally related to palmitic and myristic acids has been reported (64). 

This route is especially convenient because no over-alkylation of the anion of acetonitrile occurs. Over-alkylation can be a problem in attempts to methylate the anion of diethyl cyano-methylphosphonate (4) directly a mixture of unalkylated, monoalkylated and dialkylated products in a ratio of 1 2 1 is formed. The same problem arises with the alkylation of triethyl phosphonoacetate (11). For the preparation of a Ca-ester synthon, an alternative method to the propionitrile route is used (Scheme 7). This method has been used in the synthesis of labelled Cio-central units, described in the next Section. The starting material is acetic acid (9) which is converted into ethyl bromoacetate (10) as described above (Scheme 3). The ethyl bromoacetate (10) is reacted with triphenyl phosphine in a nucleophilic substitution reaction the phosphonium salt is formed (yield 97%). The phosphonium salt is deprotonated in a two-layer system of dichloromethane and an aqueous solution of NaOH. After isolation, the phosphorane 22 is reacted at room temperature with one equivalent of methyl iodide (19) the product consists mainly of the monomethylated phosphonium salt (>90%) which is deprotonated with NaOH, to give the phosphorane 23 in quantitative yield relative to phosphorane 22, and 23 is reacted with the aldehyde in dichloromethane. The ester product 12 can subsequently be reduced to the corresponding alcohol and reoxidized to the aldehyde 8. An alternative two-step sequence for this has also been used. First, the ester 12 is converted into the A -methyl-iV-methoxyamide (16) quantitatively by allowing it to react with the anion of A, 0-dimethylhydroxylamine as described above (Scheme 5). This amide 16 is converted, in one step, into the aldehyde 8 by reacting it with DIB AH in THF at -40°C [46]. 

Phosphonium salts are presumably intermediates. Heating alcohols with triphenyl phosphite and methyl iodide is another method for synthesis of alkyl iodides. Again, iodide displacement on a phosphonium salt Is probably involved ... 

A stirred suspension of amino(triphenyl)phosphonium bromide in THF treated dropwise with 2 eqs. BuLi in hexane at room temp, and after 30 min 10 eqs. methyl iodide in THF added - triphenylphosphine N-methylimine. Y 100%. F.e., also N-acyl-derivs., and hydrolysis to aminophosphonium salts, s. H.J. Cristau et al.. Tetrahedron Letters 29, 3931-4 (1988). 

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