Phosphoranes Triphenylphosphoranes

Ethyl (triphenylphosphoranylidene)acetate is available from FIuka AG and Trldom Chemical Inc. under the name (ethoxycarbonylmethylene)triphenyl-phosphorane and from Aldrich Chemical Company, Inc. under the name (carbethoxymethylene)triphenylphosphorane. The reagent may be prepared from triphenyl phosphine and ethyl bromoacetate by the following procedure. ... 

Because in this case an elimination reaction could occur to form an a,/ -unsaturated ester, use of two equivalents of the phosphorane should be avoided.1The (a-acylalk-ylidene)triphenylphosphorane can be subjected to a subsequent Wittig reaction with an aldehyde.[4] [5],[8]... 

However, dicarboxylic acid dichlorides treated with iminophosphoranes (Scheme 116) show a substrate-dependent reaction. Thus, o-benzodiacetyl dichlorides (321) form chloroazepinones (322) only with A -arylimino-phosphoranes. N-Alkyliminophosphoranes, upon elimination of dichloro-triphenylphosphorane and subsequent Mumm rearrangement (71M168), give the cyclic imide (323) (90S149 91T53). 

Eine neuere Methode arbeitet mit Bis-[2,2,2-trifluor-ethoxy]-triphenyl-phosphoran als Reagenz (aus Dibrom-triphenylphosphoran und Natrium-2,2,2-trifluor-ethanolat in Ether bei 0°) und ergibt gute Ausbeuten an sekundaren Aminen3 ... 

Bls(2,2,2-triflnoroethoxy)triphenylphosphorane, (C6H5)jP(OCH,CFj)2, (1). Mol. wt. 460.36, hygroscopic, stable in solution at 25 for several weeks. The phosphorane is prepared by reaction of triphenylphosphine dibromide with sodium 2,2,2-trifl uoroethoxide. 

Trippett and Walker (95) reported that cyanomethylene triphenylphosphorane did not react with ketones. In contrast to the phosphorane,... 

One of the reported syntheses of ( )-9-oxodec-2-enoic acid 392, the queen substance of the honey bee Apis mellifera, uses two ylide reactions 222). Starting from pimelic acid 385 the resonance-stabilized ylide 386 is prepared by alkylation of methylene-triphenylphosphorane 209 and the former hydrolyzed to 7-oxooctanoic acid 387. Reduction of the corresponding thiol ester 389 and olefination of the resulting aldehyde 390 with phosphorane 67 gives the ( )-2-unsaturated ester 391. The latter was hydrolyzed to pheromone 392 222) (Scheme 69). 

Trans P-sinensal 441 is obtained from the aldehyde 438 prepared by selective ozonolysis of trans-famesene 437. Wittig olefmation of 438 with 1-formylethylidene-phosphorane 440 gives trans P-sinensal 441. Reaction of 438 with 1-ethoxycarbonyl-ethylidene-triphenylphosphorane 439 yields the ethyl ester 442, from which 441 can also be obtained 237 (Scheme 77). Furthermore, a working group of the BASF synthesized a-sinensal 443 and p-sinensal 441 using Wittig reactions 238). 

Reaction of 216 with ethoxycarbonylmethylidene triphenylphosphorane gave 233, which was successfully cyclized to 238 (81MI2 87H2101) (Scheme 49). This reaction is a general method for synthesizing pyridazi-nones. The stereochemical outcome of the reaction of 216 with the phosphorane was found to afford the trans isomer 233, as anticipated from a Wittig reaction. Inspection of models indicated this isomer could not be cyclized. Its cyclization could be achieved experimentally as a consequence of the thermal preisomerization of 233 into the cis isomer 236, which led to its facile cyclization to 238. 

In the first route (Scheme 101) [20], a Wittig reaction of 590 with 1-hexylidene-triphenylphosphorane gives the Z-olefin 699 in satisfactory yield. Conversion to phosphonium iodide 700 and Wittig reaction with aldehyde 701 affords methyl 12( S)-HETE (702). In this synthesis the upper aldehyde fragment and lower phosphorane fragment are joined at the -olefin. 

WITTIG REAGENTS Carboethoxy-methylenetriphenylphosphorane. 2-Carboxy-l-methoxycarboxylethyl-triphenylphosphorane. (2-Dimethyl-aminoefhyl)triphenyfphosphonium bromide. Formylmethylenetriphenyl-phosphorane. 3-Hydroxy-3-methyF butylidenetriphenylphosphorane, lithium salt. 3-Methoxyallylidenetri-phenylphosphorane. Methylenetri-phenylphosphorane. 

Wittig Alkenation Reactions. The tosyhnethylene phosphorane is classified as a stabilized Wittig reagent because of the extra negative charge stabilization by the sulfone substituent on the yUdic carbon. Other stabilized ylides include (methoxy-or ethoxycarbonylmethylene)triphenylphosphorane, cyano-... 

Reactions with Aldehydes. The sulfonyl-stabilized phosphorane reagent has been used for Wittig alkenation of aldehydes. For example, condensation with isonicotinaldehyde gave the a,p-unsaturated sulfone as a single fisomer in 76% yield (eq 3). It is noteworthy that analogous reaction with (methylsulfonylmethy-lene)triphenylphosphorane produced the corresponding methyl-sulfonyl alkene as a 1 1 mixture of the E/Zisomers. ... 

Photochemical Reactions with Alkoxychromium Carbene Complexes. Photolysis of chromium alkoxycarbene complexes in the presence of tosylmethylene phosphorane [or ester stabilized ylides such as (methoxycarbonylmethylene)-triphenylphosphorane] under an atmosphere of carbon monoxide produced aflenes. Such reactive allenes (EWG at C1 and electron donating group at C3) hydrolyzed to give y-keto-a. -unsaturated sulfones with. stereoselectivity (eq 6). ... 

HaC O H ethanal (acetaldehyde) Phosphorane (ylid) or Wittig reagent prepared from the halide not the aldehyde (see Chapter 9) (CgH5)3P=CH2CH3 ) (CgH5)3P-CH2CH3 + ethylidine triphenylphosphorane... 

The phosphonium salt (280) is formed on treatment of ethoxycarbonylmethylene-triphenylphosphorane with phenyl-lithium and methyl iodide. The keten (281), formed by elimination of ethanol from the phosphorane, is suggested as a likely intermediate. 

The reaction of diphenylmethylene phosphorane with carbon disulfide affords polymeric diphenylthioketenes . In a similar reaction fiuorenylidene triphenylphosphorane affords the corresponding thioketene dimer . An exchange reaction is observed in the reaction of... 

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