Triphenylphosphonium methyl bromide

The unstabilized ylide, derived from triphenylphosphonium methyl bromide, is a reagent for introducing terminal olefins. Homologues of the methyl derivative deliver Z-alkenes. See section 5.2.11 for the Wittig reaction. 

Triphenylmethylphosphonium bromide A pressure bottle is charged with a solution of 55 g (0.21 mole) of triphenylphosphine in 45 ml of dry benzene and cooled in an ice-salt bath. A commercially available ampoule of methyl bromide is cooled below 0° (ice-salt bath), opened, and 28 g (0.29 mole, approx. 16.2 ml) is added to the bottle in one portion. The pressure bottle is tightly stoppered, brought to room temperature, and allowed to stand for 2 days. After this time, the bottle is opened and the product is collected by suction filtration, the transfer being effected with hot benzene as needed. The yield of triphenylphosphonium bromide is about 74 g (99%), mp 232-233°. This material should be thoroughly dried (vacuum oven at 100°) before use in preparing the ylide. 

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 discovery of junipal focused the attention of Sorensen, who had been investigating the occurrence of polyacetylenes in Com-positae, on the possibility that these acetylenes were accompanied by thiophenes. From Coreopsis grandiflora Hogg ex sweet, 2-phenyl 5-(1-propynyl) thiophene (240) was isolated and its structure confirmed by synthesis of the tetrahydro compound, 2-phenyl-5-n-propyl-thiophene. From the root of tansy, the cis and trans isomers of methyl 5-(l-propynyl)-2-thienylacrylate (241) have been isolated. The total synthesis of trans (241) was achieved by reacting junipal with methylcarbethoxy triphenylphosphonium bromide (Wittig reaction) Several monosubstituted thiophenes, (242), (243), and... 

The ylide obtained from (methyl)triphenylphosphonium bromide reacts with morpholine derivatives 597 to give phosphonium salts 598 which upon treatment with -butyllithium are converted to new ylides 599. In a reaction with aldehydes, ylides 599 form iV-(l,3-disubstituted allyl)-morpholines 602 (Scheme 94) <1996AQ138>. Another less common nucleophile that can be used for substitution of the benzotriazolyl moiety in Af-(a-aminoalkyl)benzotriazoles is an adduct of iV-benzylthiazolium salt to an aldehyde which reacts with compounds 597 to produce adducts 600. Under the reaction conditions, refluxing in acetonitrile, salts 600 decompose to liberate aminoketones 601 <1996H(42)273>. 

Reaction of 4-aryl-7-iodoperhydropyrido]2,l-c][l,4]oxazin-6-ones (07USA2007/0117839, 08WOP2008/013213) and 7-iodo-6-oxo-4-(3,4,5-tri-fluorophenyl)perhydropyrido[2,l-a]pyrazine-2-carboxylate (07USA2007/ 0117839) with P(OEt)3 at 120 °C for 2 h afforded 7-phosphonic acid diethyl esters. 3-Hydroxy-6-arylperhydropyrido[2,l-c][l,4]oxazin-4-ones first were reacted with triphenylphosphonium bromide in refluxing MeCN, then with 3-methoxy-4-(4-methyl-lH-imidazol-l-yl)benzaldehyde at ambient temperature in the presence of NEt3 to provide (Z)-3- l-[3-methoxy-4-(4-methyl-lH-imidazol-l-yl)phenyl]methylidene] derivatives (07USA2007/ 0117798, 08USA2008 /0207900). 

EthoxycarbonyI-2-methylalIy triphenylphosphonium bromide (1). Prepared by reaction of ethyl 4-bromo-3-methyl-2-butenoate with P sHs. 1... 

The aminocyclitol moiety was synthesized in a stereocontrolled manner from cis-2-butene-l,4-diol (Scheme 40)112 by conversion into epoxide 321 via Sharpless asymmetric epoxidation in 88% yield.111 Oxidation of 321 with IBX, followed by a Wittig reaction with methyl-triphenylphosphonium bromide and KHMDS, produced alkene 322. Dihydroxylation of the double bond of 322 with OSO4 gave the diol 323, which underwent protection of the primary hydroxyl group as the TBDMS ether to furnish 324. The secondary alcohol of 324 was oxidized with Dess-Martin periodinane to... 

The a proton of a substituted cyclopropane is also rendered acidic if the substituent is attached to the ring by C-P bonds. A few reports have appeared on a-substitution in such compounds.(Cyclopropyl)triphenylphosphonium bromide was converted to a (1-ethoxy-carbonylcyclopropyl)triphenylphosphonium salt 18 in 80% yield by sequential treatment with lithium diisopropylamide and ethyl chloroformate. Furthermore, some diethyl cyclopropyl-phosphonates were converted, in some cases in excellent yield, to diethyl (1-hydroxymethyl-cyclopropyl)phosphonates by treatment with lithium diisopropylamide followed by addition of an aldehyde." Thus, typically, diethyl 2-hexylcyclopropylphosphonate gave diethyl 2-hexyl-l-[hydroxy(phenyl)methyl] cyclopropylphosphonate (19b) in 90% yield on reaction with benzaldehyde. ° Other electrophiles such as acetone, acetyl chloride, acetic anhydride, and ethyl acetate, were not sufficiently reactive to undergo addition to the anion. 

Synthesis of five- and six-membered cycloalkenes has been achieved by the reaction of vinyl triphenylphosphonium bromide with ketomalonic esters of type (1), n = 1 to give 2[(2, n = 1) diethyl 3-methyl cyclopentenodicarboxylate]. 

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... 

Our next objective was to methylenate the hemiacetal 40a,so as to obtain diene 39 (Scheme 14). Standard Wittig olefination procedures on 40 with methyl triphenylphosphoranylidene, generated in situ from methyl triphenylphosphonium bromide and w-BuLi, or with KOBu-t in THF (Entries 1 and 2, Scheme 14) simply furnished unreacted starting material. Tebbe olefinations were also unsuccessful a complex mixture of products arising under the conditions investigated in Entry 3 (Scheme... 

A novel two carbon analog of 8, namely the 7-methyl-6(Z)-octadecenoic acid was recently identified in the holothurian Holothuria mexicana [27]. However, both Z and E stereoisomers were later shown to originate from the bacterium Vibrio alginolyticus [27]. Therefore, the real source of 7-methyl-6-octadecenoic acid is also bacterial. Both Z and E isomers of 7-methyl-6-octadecenoic acid were synthesized as shown in Fig. (9). In this short synthesis (little more than one step) a Wittig coupling of (6-carboxyhexyl)triphenylphosphonium bromide with 2-tridecanone readily afforded a 1 1 mixture of 7-methyl-6(Z)-octadecenoic... 

Erylus formosus [45], was also reported by Kulkami et al. [53]. As shown in Fig. (19), a common bifunctional nine-carbon aldehyde was used for both syntheses. Both syntheses started with the DHP monoprotection of 1,4-butanediol, followed by subsequent PCC oxidation to the corresponding aldehyde. Reaction of this butanal with (4-carboxybutyl)triphenylphosphonium bromide resulted in the corresponding THP protected olefinic acid that was further deprotected and esterified to the methyl ester. A second oxidization with PCC afforded the desired intermediate methyl 8-formyloct-5-enoate which secured the cis A5 double bond in the final targets, Fig. (19). The... 

Several 6-substituted pyran-2-ones have been synthesized from dehydroacetic acid (49) by bromination and conversion of the bromo-methyl group into the triphenylphosphonium bromide, and by bromination of the methyl ether (50).59 Further examples of the use of pyran-2-ones as dienes in the Diels-Alder reaction have been reported.60 61... 

Addition of lithiated N-methylindole to ethyl oxalate in ether and base hydrolysis gave a glyoxylic acid which was converted to its methyl ester (510) with diazomethane. Treatment of this ester with methylene triphenylphosphonium bromide and butyllithium under reflux gave acrylate 508 in 40% overall yield. 

---