Methyl triphenyl phosphonium bromid

Methyl triphenyl phosphonium bromide (0.56 mmol) was dissolved in 10 ml of THF and treated with 1.6 M -butyl lithium (0.64 mmol) in hexane solution at 0°C. The solution was stirred for 30 minutes at 0°C and then treated with the step 2 product (0.36 mmol) and stirred an additional 2 hours at ambient temperature. The solution was treated with dilute hydrochloric acid, extracted with chloroform, dried over MgSC>4, and concentrated. The residue was purified by silica gel column chromatography using chloroform/hexane, 2 1, respectively, recrystallized using CH2CI2/ methanol, and 100 mg of product isolated. 

Another highly versatile building block derived from diacetone-glucose 54 is the 1,2-acetonide of 3-C-methyl-a-D-allose in its furanoid form 57, which has been utilized as the key compound in a convergent total synthesis of ACRL Toxin I (63). Its elaboration from 54 starts with a pyridinium dichromate / acetic anhydride oxidation (64), is followed by carbonyl olefination of the respective 3-ulose with methyl (triphenyl)phosphonium bromide and hydrogenation (— 55 56), and is completed by acid cleavage of the 5,6-isopropylidene group. This four-step process 54 -> 57, upon optimization of reaction conditions and workup procedure, allows an overall yield of 58 % (63), as compared to the 22 % obtained previously (65). 

Cesium fluoride-Tetraalkoxysilanes, 69 Hexamethylphosphoric triamide, 142 Methyl acrylate, 183 a-Methylbenzylamine, 185 Methyl vinyl ketone, 193 Potassium t-butoxide, 252 Potassium f-butoxide-Xonotlite, 254 Potassium fluoride-Alumina, 254 Tin(II) trifluoromethanesulfonate, 301 Titanium(IV) chloride, 304 Trityl perchlorate, 339 Vinyl(triphenyl)phosphonium bromide, 343... 

Heterocycles Acetylacetone. N-Aminophthalimide. Boron trichloride. Dichloro-formoxime. Oicyanodiamide. Dicyclohexylcarbodiimide. Dietboxymethyl acetate. Diethyl oxalate. Diketene. Dimethylformaniide diethylacetal. Diphenyldiazomethene. Ethyl ethoxy-methylenecyanoacetate. Formaldehyde. Formamide. Formamidine acetate. Formic acid. Glyoxal. Hydrazine. Hydrazoic acid. Hydroxylamine. Hydroxylamine-O-sulfonic acid. Methyl vinyl ketone. o-Phenylenediamine. Phenylhydrazine. Phosphorus pentasullide. Piperidine. Folyphosphoric acid. Potassium diazomethanedisulfonate. Sodium ethoxide. Sodium nitrite. Sodium thiocyanate. Tetracyanoethylene. Thiosemicarbozide. Thiourea. Triethyl orthoformate. Tris-formaminomethane. Trityl perchlorate. Urea. Vinyl triphenyl-phosphonium bromide. 

There is no general solvent that is useful for all reactions, and BTF naturally has its limitations. In addition to the limitations posed by the freezing point, boiling point and chemical stability mentioned before, BTF is not very Lewis-basic and therefore is not a good substitute for reactions that require solvents like ethers, DMF, DMSO, etc. Not surprisingly, ions are not readily dissolved in BTF and many types of anionic reactions do not work well in BTF. For example, attempted deprotonations of esters and ketones with LDA in BTF were not successful. Reaction of diethyl malonate with NaH (5 equiv) and reaction with Mel[72] (6 equiv) in BTF was very heterogeneous and yielded 60% of the di-methylated product, compared to 89% in THF. No reaction was observed if the same malonate anion was used as a nucleophile in a Pd-catalyzed allylic substitution reaction in BTF (see 3.7). Wittig reactions also did not work very well in BTF. The ylid of ethyl triphenyl phosphonium bromide [73] was formed only slowly in BTF, and the characteristic deep red color was never obtained. 

Mechanical Behavior. The ionomers, - poly[Isobutylene-co-(4-methyl styrenyl, triphenyl phosphonium bromide or tetraphenyl borate)] were found to be different in physical appearance(hard and strong) and tougher than the starting material, the Exxpro elastomer. The mechanical properties of these quaternary phosphonium... 

Carboxylic acid 125 was coupled with ethanolamine or L-serine methyl ester hydrochloride in the presence of EDCI, HOBt, and EtsN to afford the corresponding p-hydroxy amides, which were cyclized using bis(2-methoxyethyl)aminosulfur trifluoride (Deoxo-Fluor) to afford oxazolines (149 and 150, Scheme 24) [56, 57]. Oxazoline 150 was converted to oxazole 151 in 80% yield by treatment with bromotrichloromethane and DBU, conditions which did not lead to epimerization at C-8 [57], A variety of oxadiazoles (152-158) have been produced in 10-56% yield by treating carboxylic acid 125 with appropriate amidoximes in the presence of EDCI and HOBt followed by heating in toluene (Scheme 24) [44, 57, 58]. These conditions led to some epimerization at C-8, necessitating purification by HPLC. Carboxylic acid 125 was treated with either (2-hydroxybenzyl)triphenyl- or (2-thiobenzyl)triphenyl phosphonium bromide in the presence of CDMT and EtsN to afford the benzofuran (159) and benzothiophene (160) products in 26 and 35% yield, respectively (Scheme 24) [58]. 

PRA Prasad, M., Moulik, S.P., Wardian, A.A., Moore, S., Bonunel, A. van, and Palepu, R., Alkyl (Cio, C12, Ci4 and Cie) triphenyl phosphonium bromide influenced cloud points of nonionic surfactants (Triton X 100, Brij 56 and Brij 97) and the polymer poly(vinyl methyl ether). Coll Polym. Sci., 283, 887, 2005. 

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). 

Finally, achiral phosphonium salts have been explored as Lewis acid catalysts in some other reactions. The examples are briefly listed here but are not discussed in more detail. Phosphonium salts have been used as catalysts for the N,N-dimethylation of primary aromatic amines with methyl alkyl carbonates, giving the products in good yields [78]. Furthermore, acetonyl(triphenyl)phosphonium bromide has been used as a catalyst for the cydotrimerization of aldehydes [79] and for the protection/deprotection of alcohols with alkyl vinyl ethers [80, 81). Since the pKj of the salt is 6.6 [82-85], the authors proposed that alongside to the activation of the phosphonium center, a Br0nsted add catalyzed pathway is possible. 

Wittig reactions Carbomethoxymethylenetriohenylphosphorane. Cyclopropyltriphenyl-phosphonium bromide. l,5-Diazabicyclo[4.3.0]nonene-5. Diethyl cyanomethylphosphonate. p-Diphenylphosphinobenzoic acid. Diphenylsulfonium isopropylide. Diphenyl triphenyl-phosphoranylidenemethylphosphonate. Ethyl(dimethylsulfuranylidine)acetate. Ethylene oxide. Hexamethylphosphorous triamide. Methoxymethylenetriphenylphosphorane. Meth-ylenemagnesium bromide (chloride). Simmons-Smith reagent. Sodium 2-methyl-2-butoxide. 

The adduct obtained by the reaction of triphenyl(prop-2-ynyl)phosphonium bromide with o-aminobenzophenone (Y 95%) refluxed overnight with NaH in acetonitrile 2-methyl-4-phenylquinoline (Y 64%). F. e. and heterocyclics s. E. E. Schweizer et al., Chem. Commun. 1973, 7. 

Phosphonium, (carboxymelhyl)triphenyl-, bromide, ethyl ester, 70, 246 Phosphonous dichloride, phenyl- (644-97-3), 70, 273 Phthalimide, N-(3-bromopropyl)-, 70. 195 Piperidine, 2-methyl- (109-05-7), 70, 265 Pirkle Type 1-A column, 70, 64... 

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