Triphenylphosphonium 3,3-Dimethyl

Reflux 6.9 g triphenylphosphine and 6.6 g lauryl bromide (or equimolar amount of homolog) in 40 ml xylene for 60 hours. Remove solvent and wash residue with 5X20 ml ether (by decanting) to get 11 g lauryl triphenylphosphonium bromide (I). To a stirred suspension of 5.6 g (0.011M)(I) in 50 ml ether add 0.01M butyllithium solution (see Organic Reactions 8,258(1954) for preparation). Stir Vz hour at room temperature and slowly add 1.66 g 3,5-dimethoxybenzaldehyde (preparation given elsewhere here) in 10 ml ether over Vi hour. After 15 hours, filter, wash filtrate with water and dry, evaporate in vacuum. Dilute residue with pentane, filter and remove solvent. Dissolve the residual oil in 25 ml ethyl acetate and hydrogenate over O.lg Adams catalyst at one atmosphere and room temperature for 2 hours. Filter and evaporate in vacuum to get the 5-alkylresorcinol dimethyl ether which can be reciystallized from pentane and demethylated as described elsewhere here. 

When 5,5-dimethyl-1,3-hexadiynyl(phenyl)iodonium triflate is mixed with two equivalents of triphenylphosphine in toluene, a mixture of bisphosphonium triflates is produced (equation 76)34. This transformation apparently involves the initial formation of (5,5-dimethyl-l,3-hexadiynyl)triphenylphosphonium triflate followed by competing Michael and conjugate Michael reactions of this compound with a second mole of triphenylphosphine. The ( -geometry about the carbon-carbon double bonds in both products has been established by NMR analysis34. 

Methylenebis(triphenylphosphonium)-bromide, 446 Methylene blue, 201 Methylene bromide, 273 Methylene chloride, 69,72,79,180,273,398 Methylenecyclohexane, 226, 349 Methylenecyclohexane oxide, 171 1 a, 2a-Methylene-16a, 17a-(dimethyl-methylenedioxy)-A,s-pregnadiene-3, 20-dione, 172 Methylene iodide, 273, 371 Methylenemagnesium bromide (iodide), 273-274... 

An analogous rearrangement was observed with the preparation of l-benzyl-4,9-dihydro-4,6-dimethyl-7-(3-methyl-l -butenyl)-l //-imidazo[l, 2-a]purin-9-one (185a) by a three-step synthesis from 1-benzyl-4,9-dihydro-4,6-dimethyl-7-(hydroxy-methyl)-l//-imidazo[l,2-a]purin-9-one (183), which reacted with phosphorus tribromide to the corresponding 7-bromomethyl derivative 184a and with triphenylphosphine to the triphenylphosphonium bromide 184b. The latter reacted... 

Having assembled the bicyclic framework, attention was directed toward introduction of the diylophile. Deprotection of the masked aldehyde in 46 and 47 was most efficiently accomplished using 70% aqueous acetic acid at 50-60 °C for 5 days (85% and 95% yield, respectively). The dimethyl dicarbamate was subjected to saponification with potassium hydroxide in refluxing ethanol for 1.5 hours, whereafter the in situ oxidation with potassium ferricyanide at 0 °C gave rise to the dizaene 48 in yields ranging from 76-86%. We were gratified to observe that treatment of 48 with triphenylphosphonium methylide in THF at room temperature led to the desired diyl precursor 41 in 56-83% yield. 

Antipyrinylmethyl)triphenylphosphonium iodide 3 52 (Dimethylaminomethyl)antipyrine methiodide (3.87 g, 0.01 mole) and triphenylphosphine (3.93 g, 0.015 mole) in dimethyl-formamide (25 ml) are boiled under reflux for 3 h while nitrogen is passed through the solution, the trimethylamine evolved (95%) being absorbed in O.lN-hydrochloric acid. The reaction mixture is then freed from solvent, and the residue is powdered and boiled with benzene which removes unchanged phosphine. There remains a crude product (5.6 g, 96 %) which after recrystallization from water has m.p. 193-194° (3.9 g, 67%). 

The same ylide was used by Isler and his collaborators1013 for synthesis of polyene carboxylic acids. / ,y-Unsaturated carboxylic acids are accessible by starting from (2-ethoxycarbonylethyl)triphenylphosphonium chloride1014 and, e.g., cyclohexanone1015 in dimethyl sulfoxide-tetrahydrofuran containing sodium hydride ... 

AMINOALKYLATION (2-Dimethyl-aminoethyl)triphenylphosphonium bromide. N-(Diphenylmethylene)-methylamine. 

A. p-Xylylene-bis triphenylphosphonium chloride). A mixture of 262 g. (1.0 mole) of triphenylphosphine (Note 1) and 84 g. (0.48 mole) of -xylylene dichloride (Note 2) in 11. of dimethyl-formamide is heated at reflux with stirring for 3 hours (Note 3). The mixture is then allowed to cool to room temperature with stirring, and the white crystalline solid is collected, washed with 100 ml. of dimethylformamidc followed by 300 ml. of ether, and... 

Derivatization of Fatty Acids Derivatized fatty acids have been analyzed to improve ionization and fragmentation characteristics. The FAB spectra of these derivatives are structurally more informative, and fragmentations predominantly occur via CRF processes. One such example is the application of aminoethyl-triphenylphosphonium (AETPP) bromide derivatives to characterize fatty acids structurally by FAB-MS/MS [12]. Other examples include derivatives of aminon-aphthalenesulfonic acid (ANSA), aminobenzenesulfonic acid (ABSA), picolinyl ester, yV-methyl-2-alkylimidazoline (MIM), and dimethyl- (DMAE) and trimethy-laminoethyl (TMAE) esters [8, and references therein], ESI-MS/MS spectra of underivatized and ANSA derivatives of docosahexaenoic acid are compared in Figure 12.8. 

The B3P86/6-31G mechanistic results for the Wittig reaction of acetaldehyde in vacuo and in tetrahydrofuran (THF) solution with an unsubstituted trimethylphospho-nium or triphenylphosphonium ylide have been compared to those obtained at the same levels for the reaction of triphenylphosphonium ylide with a bulky chiral aldehyde, (2S, 3/ )-2,4-dimethyl-3-pyrrol-l-yl-pentanal. ° Betaine-type intermediates were found not located in vacuo when trimethylphosphonium yUde was used, while only a gauche betaine is obtained using triphenylphosphonium ylide. Conversely, in THF, the concerted and stepwise mechanisms are both represented and show TSl/TSb barriers, which are negligibly small for unsubstituted triphenylphosphonium yUde. 

Bis(trimethylsilyl)-1,4-xylene bis(triphenylphosphonium bromide) (3). A solution of 2,5-bis(trimethylsilyl)-l,4-bis(bromomethyl)benzene and tri-phenylphosphine in dimethyl formamide (DMF) is stirred and healed to reflux for 24 h. The resulting mixture is poured into diethyl ether. After filtration and vacuum drying, the monomer (3) is obtained as a white powder. 

Mitsunobu-like Processes. Triphenylphosphonium 3,3-dime-thyl-l,2,5-thiadiazolidine 1,1-dioxide (1) can be conveniently utilized as a stable source of [PhsP+J in the promotion of Mitsunobu-like processes. By analogy with the betaine generated by reaction of DEAD and triphenylphosphine, protonation of zwitterionic species 1 by an acidic component HX generates ion pair 2 which on subsequent reaction with an alcohol (ROH) affords oxyphosphonium species (3) and 3,3-dimethyl-1,2,5-thiadiazolidine-1,1-dioxide (4). Finally, Sn2 displacement reaction, occurring with Walden inversion of the alcohol stereochemistry, leads to the coupled product R-X and triphenylphosphine oxide (TPPO) (eq 1). 

Dimethyl-2,6-octadienyl)triphenylphosphonium bromide stirred and refluxed 20 hrs. in water (7-hydroxy-3,7-dimethyl-2-octenyl)triphenylphospho-nium bromide. Y 90%. J. D. Surmatis and A. Ofner, J. Org. Ghem. 28, 2735 (1963). 

A solution of 66.1 gm (0.25 mole) of o-xylylene dibromide and 142.5 gm (0.55 mole) of triphenylphosphine in 500 ml of dimethyl-formamide (DMF) is heated under reflux. After the first 10-15 min, a colorless crystalline solid begins to separate and the refluxing is continued for 3 hr. The mixture is cooled, filtered, and the solid is washed with DMF and ether. After air-drying, 175.9 gm (89.4%) of pure o-xylylene bis(triphenylphosphonium) dibromide, mp > 340°C is obtained. 

Dimethylselenoniododecyl) triphenylphosphonium dichloride Systematic name (12-Dimethyl-selaniumyldodecyl)triphenyl-phosphanium. 

---