Tetrabutylammonium fluoride hydrate

Tetrabutylammonium fluoride hydrate Ammonium, tetrabutyl-, fluoride, hydrate (8,9) (22206-57-1)... 

C-19 methyl functionality in the tetracyclic ketone 164, the Nt-H group was alkylated with the optically active i .-tosylate 224 (which was in turn obtained from the R propargylic alcohol via a two-step sequence) in aceto-nitrile/K2C03, followed by treatment with tetrabutylammonium fluoride hydrate to obtain the acetylenic ketone 225 in 96% yield. The terminal alkyne in 225 was converted into the iodoolefm functionality by treating with dicyclohexyhodoborane [I-B(Cy)2], followed by protonolysis. The iodo-olefin 226 was obtained in 74% yield. It was subjected to a Pd-catalyzed a-vinylation to obtain the key C-19 methyl-substituted pentacy-clic system 227. This was followed by a Wittig/hydrolysis/epimerization... 

The deprotonated form of compound 12 contains both an anionic carboxylate group and an anion-receptor calixpyrrole macrocycle. X-ray quality crystals of the calixpynole carboxylate 12 were obtained by slow cva X)ralion of a dichloromethane solution of 12 in the presence of excess tetrabutylammonium fluoride hydrate. Interestingly, the crystals did not contain any fluoride anions within the lattice. Rather, the structure was found to consist of the tetrabutylammonium caIix 4 pyrrole carboxylate salt. The structure of the salt also revealed that the calixpyrrole carboxylate. sell-assembles in the solid state with the carboxylate of one calixpyrrole bound to the pyirolic array of an adjacent calixpyrrole and vice versa. This forms a dimeric cyclic structure as indicated in Figure 13. In this... 

Numerous organometal additions onto ene-sulfones are reported. A sulfonyl group secures powerful activation, and moreover, it can be readily removed by reduction or elimination. This makes the sulfonyl function a cherished auxiliary in natural product synthesis. A rational entry to d-(+)-carbacyclin (in 4.7% overall yield by a triply convergent synthesis) exemplifies the approach. The addition of the silyl-protected trans-(5)-3-hydroxy-l-octenyllithium onto cyclopentenyl phenyl sulfone 162 triggers a condensation with the allyl chloride tail. The carbacyclin skeleton constructed, the sequence is terminated by protodesilylation (using tetrabutylammonium fluoride hydrate), reductive removal (with lithium) of benzyl and benzenesulfinyl, and selective oxidation of the primary alcohol site (Scheme 1-117). ... 

Thus removal of water from classical rather inactive fluoride reagents such as tetrabutylammonium fluoride di- or trihydrate by silylation, e.g. in THF, is a prerequisite to the generation of such reactive benzyl, allyl, or trimethylsilyl anions. The complete or partial dehydration of tetrabutylammonium fluoride di- or trihydrate is especially simple in silylation-amination, silylation-cyanation, or analogous reactions in the presence of HMDS 2 or trimethylsilyl cyanide 18, which effect the simultaneous dehydration and activation of the employed hydrated fluoride reagent (cf, also, discussion of the dehydration of such fluoride salts in Section 13.1). For discussion and preparative applications of these and other anhydrous fluoride reagents, for example tetrabutylammonium triphenyldifluorosilicate or Zn(Bp4)2, see Section 12.4. Finally, the volatile trimethylsilyl fluoride 71 (b.p. 17 °C) will react with nucleophiles such as aqueous alkali to give trimethylsilanol 4, HMDSO 7, and alkali fluoride or with alkaline methanol to afford methoxytri-methylsilane 13 a and alkali fluoride. 

T) mit Hexamel hylsilazan358 4,67 g (29 mmol) Hexamethylsilizan, 16mmol 1,2-Diacyl-hydrazin und 5,04 g (16 mmol) Tetrabutylammonium-fluorid-Tris-hydrat erhitzt man 21 -48 h unter Stiekstoff zum Sie-den. Nach Destination oder durch Umkristallisation erhalt man die 2,5-disubstituierten 1,3,4-Oxadiazole Ausbeute 63-81%. 

Tetrabutylammonium fluoride is very hygroscopic. A drybox may be used to avoid rapid manipulation of the fluoride in the atmosphere and exposure of the reagent in the storage vessel to moisture. Alternatively, hydrated tetrabutylammonium fluoride (Note 11) can be dried in the reaction vessel and used directly. 

Deprotection of TBS ethers is not limited to acidic reagents fluoride is also effective and the most popular reagent is tetrabutylammonium fluoride (TBAF). which is available commercially as the trihydrate (mp 62-63 °C). Benzyltri-methylammonium fluoride has also been recommended in cases where TBAF has failed.72 The solid hydrate is highly hygroscopic and so it is usually dispensed as a 1.0 M solution in THF. The presence of water diminishes the effectiveness of TBAF owing to the tenacious hydration of fluoride ion however, the water cannot be completely removed — nor should it — because anhydrous TBAF is... 

Advances of the past three decades, however, have produced alternatives to the heavy metal-based cellulose solvents. Prominent among them are dimethylacetamide/LiCl (DMAc/LiCl) N,MMN-0 hydrate (NMMO) tetrabutylammonium fluoride/DMSO (TBAF/DMSO) and potassium thiocyanate/DMSO [48]. While many of these solvents have gained significant popularity among laboratory chemists, only the amine oxide solvent, N,MMNO, has achieved industrial practicality. This will be discussed in the section on regenerated cellulose fibers. Several other important physical properties of cellulose are given in O Table 4. 

Albanese, D., Landini, D., Penso, M. Hydrated Tetrabutylammonium Fluoride as a Powerful Nucleophilic Fluorinating Agent. J. Org. Chem. 

Almost anhydrous tetrabutylammonium fluoride, prepared by heating the corresponding hydrate at 40-45°C, is an excellent source of naked fluoride in organic synthesis. ... 

DMPO is more difficult to oxidize than PBN by about 0.2 V (Table 1) and is therefore expected to engage in spin trapping via its radical cation with greater difficulty, as found for the 0sCl6-4-N02-PBN reaction. Only acetate ion, tetramethylsuccinimide ion and triethyl phosphite gave the corresponding adducts upon oxidation with TBPA + in dichloromethane in the presence of DMPO, whereas fluoride ion gave the hydroxyl adduct. The latter was probably formed from water available from the unavoidable hydration shell around fluoride ion in its tetrabutylammonium salt. 

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