Tetrabutylammonium iodide phase transfer catalyst

Boujlel and Simonet used an electrochemical method to prepare a group of similar compounds, including compound ]5, shown in Eq. (3.41). In a typical case, benzil was reduced in DMF solution at the dropping mercury electrode in the presence of tetrabutylammonium iodide, used in this case as a supporting electrolyte rather than phase transfer catalyst. In the presence of diethylene glycol ditosylate, compound 15 (mp 77— 78°) was isolated in 10% yield. Using the same approach, acenaphthenedione was reduc-tively cyclized with triethylene glycol ditosylate to afford the product (mp 84—85°, 42% yield) shown in Eq. (3.42). 

The synthesis of anastrozole (Scheme 3.3) began with an 8 2 displacement of commercially available 3,5-fc (bromomethyl)toluene (19) using potassium nitrile and a phase-transfer catalyst, tetrabutylammonium bromide (Edwards and Large, 1990). The resulting fcw-nitrile 20 in DMF was then deprotonated with sodium hydride in the presence of excess methyl iodide to give the fc -dimethylated product 21. Subsequently, a Wohl-Ziegler reaction on 21 was carried out using A-bromosuccinamide (NBS), and a catalytic amount of benzoyl peroxide (BPO) as the radical initiator. Finally, an Sn2 displacement of benzyl bromide 22 with sodium triazole in DMF afforded anastrozole (2) as a white solid. 

Me2S04 is used under basic conditions as source of a methyl nucleophile. It can thus transform alcohols into methyl ethers or transform amines into the methylamine. Usually a phase transfer catalyst such as tetrabutylammonium iodide is added to the aqueous basic solution.4 Other reagents to create methyl ethers include iodomethane or trimethoxonium tetrafluoroborate (Meerwein s reagent).5... 

Benzophenone hydrazone (5.88 g, 20 mM) was dissolved in methylene chloride (20 ml) and over-layered with 1 M sodium hydroxide (40 ml) containing, as phase transfer catalyst, tetrabutylammonium sulfate (0.68 g) and sodium iodide (300 mg). The cathode half cell contained 1 M sodium hydroxide (60ml). The whole cell was cooled to 0°C, the anode compartment stirred and electrolysed at a current of 50 mA. Formation of DDM was followed using the DDM absorption peak at 525 nm. The chart obtained was as shown in Figure 2. 

Flavanones and Isoflavanones.- Reaction of the aryl benzyl ketone (120) with formaldehyde and dimethylamine has provided a new synthesis of isoflavanones in good yield.126 The same ketones can be cyclized to isoflavanones in good yield by treatment with di-iodomethane, a phase transfer catalyst (tetrabutylammonium iodide) and sodium thiosulphate.127 Flavanones react with hydroxylamine hydrochloride in ethanol-pyridine to give the oxime and not the oxazoline as previously claimed but when the oxime was heated with trifluoroacetic acid, the oxazoline was formed.128 The first triphenylmethane derivative to be found in nature, the flavanone melanervin (121), has been synthesized. Ammals (not animals, as printed in the abstract ) such as (122) have been applied to the... 

Phase-transfer catalysis has been investigated for the model displacement reaction of bromooctane with iodide. The first is dissolved in an organic solvent (chlorobenzene) and the latter in an aqueous phase. The phase-transfer catalyst used was the tetrabutylammonium ion, dissolved in the organic phase [52]. Using a hydrophobic membrane-contactor device, conventional coalescence problems were avoided. Additionally, as a result of the interfacial area being known, operation of the reactor can be performed with greater flexibility. 

Reagents and Equipment. Use the same apparatus as in Experiment [22A] for this synthesis. Weigh and add 150 mg (1.2 mmol) of 4-ethylphenol to the reaction vial followed by 250 xL of 25% aqueous sodium hydroxide solution ( ). Stir the mixture at room temperature until dissolution occurs. The phase-transfer catalyst (tetrabutylammonium bromide (Bu4N Br ), 15 mg, 0.05 mmol) is now added, followed by 90 xL (205 mg, 1.45 mmol) of methyl iodide. 

After dissolution of the sodium hydroxide, weigh arid add 150 mg of the phase-transfer catalyst, tetrabutylammonium bromide, followed by 2.05 g (900 jlL) of methyl iodide (in the hood) using an automatic delivery pipet ( h... 

Another useful variation of the phosphine-free Suzuki reaction uses a heterogeneous system with neat water as solvent and tetrabutylammonium chloride as promoter and phase-transfer catalyst (Scheme 42). Aryl bromides were shown to give higher yields than aryl iodides, because of inhibition of phase-transfer by the hberated iodide ion. ... 

Triazole Derivatives. The synthesis of 4,5-disubstituted 1,2,3-triazoles using sodium polystyrylsulfinate resin 43 was first reported by Huang and coworkers (Scheme 12.17). The synthesis involved the reaction between arylpropiolates and sodium azide followed by oxidation. Resin-bound ethyl polystyrylsulfonylacetate 68 was prepared using ethyl 2-bromoacetate in DMF with potassimn iodide and tetrabutylammonium iodide as a phase transfer catalyst. Subsequent reaction of resin 68 with benzaldehyde using piperidine as a catalyst afforded arylidene polystyrylsulfonyl acetate 69. CycUzation of 69 with sodium azide in DMSO at 120°C for 5h afforded the 1,2,3-txiazoles 70a. 

A soln. of tosylmethylisocyanide, ethyl iodide, and tetrabutylammonium iodide as phase transfer catalyst in methylene chloride stirred vigorously 3 hrs. at 0 with aq. 30%-NaOH product. Y 90%. F. e. s. A. M. van Leusen, R. J. Bouma, and O. Possel, Tetrah. Let. 1975, 3487. 

Trimethylsulfonium iodide undergoes ylid formation by reaction with 50% aqueous sodium hydroxide in the presence of catalytic tetrabutylammonium iodide [16]. The ylid thus formed reacts with aldehydes and ketones to form the corresponding epoxides (Eq. 14.7). The yields with aldehydes are considerably better than those with ketones. The fact that the reaction is slow (48 hours) may be due to the iodide of the catalyst. On the other hand, lauryldimethylsulfonium chloride undergoes reaction with ketones and aldehydes to yield epoxides under alkaline phase transfer conditions considerably more rapidly (6—10 hours). The enhanced rate of this methylene transfer reaction is probably due to the greater organic solubility of the lauryldimethylsulfonium cation [17]. Catalyst poisoning is observed with lauryldimethylsulfonium iodide. Similar reactions have been conducted under ion pair extraction conditions [18]. 

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