Tetrabutyl ammonium fluoride

Trimethylsilylethynylpyrazole was deprotected by treatment with tetrabutyl-ammonium fluoride (TBAF) to give monosubstituted acetylene in 90% yield. (96ADD193). The same conditions were used to cleave the trimethylsilyl group in l-tetrahydropyranyl-3-carboxyethyl-4-[2-(trimethylsilyl)ethynyl]pyrazole (96INP 9640704). 

Intramolecular cyclization of 2-phenysulfonylmethyl lactam 3 took place upon reaction with lithium hexamethyldisilazan via generating its a-sulfonyl carbanion to give a cyclized postulated intermediate that can be quenched with trimethylchlorosilane to afford the stable silyl ketal 4. The later ketal was desulfonylated by Raney-Ni and desilylated through treatment with tetrabutyl ammonium fluoride (BU4NF) to afford the carbacephem 5 (94M71) (Scheme 1). 

The enantioselective addition of a nucleophile to a carbonyl group is one of the most versatile methods for C C bond formation, and this reaction is discussed in Chapter 2. Trifluoromethylation of aldehyde or achiral ketone via addition of fluorinated reagents is another means of access to fluorinated compounds. Trifluoromethyl trimethylsilane [(CF SiCFs] has been used by Pra-kash et al.87 as an efficient reagent for the trifluoromethylation of carbonyl compounds. Reaction of aldehydes or ketones with trifluoromethyltrime-thylsilane can be facilitated by tetrabutyl ammonium fluoride (TBAF). In 1994, Iseki et al.88 found that chiral quaternary ammonium fluoride 117a or 117b facilitated the above reaction in an asymmetric manner (Scheme 8-42). 

Kambe and Yasuda19 discovered the effectiveness of the fluoride as a Henry reaction catalyst. Since then, the use of diverse fluorides is a common method to catalyze nitro aldol condensations, since they provide mild conditions that are particularly convenient for sensitive products as carbohydrates. The most common fluorides are potassium fluoride20 and tetrabutyl ammonium fluoride.21 A recent example relates to the TBAF catalyzed addition of nitroethanol to the D-glucose derivative 18, to give nitro sugars 19 (Scheme 8).22... 

Gao SJ, Tsai CH, Yao CF (2009) A simple and green approach for the synthesis of tetrahydrobenzo a xanthen-ll-one derivatives using tetrabutyl ammonium fluoride in water. Synlett 949-954... 

Scheme 34. Reagents and conditions (a) Et2NH, EtsN, 10mol% tetrabutyl ammonium fluoride (TBAF), DMSO, 70°C (b) PhLi, THF, -78°C (c) 10% HCI aq rt.

Eine effektive, reversible Schutzgruppe fur Benzimidazole ist l-Chlormethoxy-2-trimethylsilyl-ethan (SEM — Cl), das in Dimethylformamid zu l-[(2-Trimethylsilyl-ethoxy)-methoxy]-benz-imidazol [50% Sdp. 220°/0,2 Torr (26,7 Pa)] kondensiert. Die so geschiitzten Heterocyclen sind wesentlich weniger feuchtigkeitsempfindlich als die (l-Diethoxy-methyl)-Derivate (s.S.357). Man kann die SEM-Schutzgruppe in siedendem Tetrahydrofuran mit Tetrabutyl-ammonium-fluorid leicht wieder entfernen508. 

Reactions of aryl or alkyl bis(siloxy)isopropyl ethers with tetrabutyl-ammonium fluoride-mesyl fluoride reagent lead to replacement of one siloxy group by fluorine and dehydrosiloxylation, providing an efficient access to fluoroisopropenyl ethers, which are useful as specific building blocks in drug design The reactions proceed via the intermediate allyl methanesulfonates [30, 31] (equation 23)... 

Substitution of the acetate group at the C-3 position of the /3-sultam 105 can occur by reaction with silyl enol ethers in the presence of zinc iodide or zinc chloride. When the diazo compound is used, after desilylation with tetrabutyl-ammonium fluoride (TBAF), photochemical cyclization gives the bicyclic /3-sultam 106 as a mixture of two cis/ fra -diastereoisomers. When silyl enol ethers derived from cyclic ketones are used, the substitution product is stabilized by a retro-Michael-type reaction leading to open-chained sulfonamides 107 (Scheme 31) <1997LA1261>. 

The combination of fluoride ions and enol silyl ethers provides a useful method for the generation of enolate anions [9]. Watts, Haswell and coworkers applied a borosilicate glass microreactor, having channel dimensions of 100 pm x 50 pm and equipped with an electrosmotic flow (EOF) pumping system, to the C-acylation of enolate anions, which leads to 1,3-diketones [10,11]. A THF solution of tetrabutyl-ammonium fluoride (TBAF) was placed in reservoir A, a THF solution of benzoyl... 

The O-silyl derivatives of some tertiary bicyclic or tricyclic alcohols with a cyclopropane moiety upon treatment with IOB, followed by addition of tetrabutyl-ammonium fluoride, underwent oxidation with ring expansion and formation of a,/J-unsaturated ketones, for example [22] ... 

Thus, the a- and P-trimers of thiobenzoyltrimethylsilane 5 and 6 were converted stereospecifically to the a- and P-trimers of thiobenzaldehyde24 by reaction with tetrabutyl ammonium fluoride (TBAF) (Scheme 19). 

The Step 1 product (1.735 mmol) dissolved in 20 ml THF at 0°C was treated with 3.81ml 1M tetrabutyl ammonium fluoride in THF, then stirred 15 minutes, and... 

The SLibstitiilion of an inorganic ester group, such as /t-toluenesulfonate (tosylate), methanesul-I onate (mesylate), trifluoromethancsulfonate (triflate), cyclic sulfate, etc., by fluorine is one of the most important methods for the introduction of fluorine into aliphatic molecules. It is an indirect method for the substitution of a hydroxy group with a fluorine. By using an in situ esterification, e.g, with trifluoromethancsulfonyl fluoride, and fluorination, c.g. with tetrabutyl-ammonium fluoride, it also provides a one-pot reaction for realizing this reaction. 

To probe for one-dimensional diffusion, we synthesized DNA/RNA chimeric oligonucleotides. Special precautions were taken to avoid ribonuclease contamination during synthesis, purification, and use of these chimeras. For example, all water was treated with diethylpyrocarbonate before exposure to the chimeras. Ribonucleotide 2 -hydroxyl groups were deprotected with 1 M tetrabutyl ammonium fluoride in dimethyl formamide (Aldrich Chemical Milwaukee, WI). Purified oligonucleotides were labeled on the 5 end with [y-32p]ATP (duPont Wilmington, DE) by T4 kinase (Promega Madison, WI), and desalted with a Nick gel filtration column (Pharmacia Uppsala, Sweden). 

Alkynylsilanes will react with tributyltin oxide in an analogous fashion if tetrabutyl-ammonium fluoride is used as a catalyst.96 The hexamethyldisiloxane which is formed can readily be removed under reduced pressure, and yields are excellent (equation 8-50). 

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