Tert Butyl fluoride

Butyl ether, dl48 Butyl ethyl ketone, hi5 tert-Butyl fluoride, f22... 

In the absence of direct calorimetric data for the enthalpy of formation of tert-butyl fluoride, what happens if we use the value of-351.1 kJ mol"1 derived elsewhere in this study. So doing, we conclude the resonance energies of the halobenzenes are all negative and near-... 

Both methyltriethylphosphonium fluoride and methyltributylphospho-nium fluoride have been prepared The latter generates benzyl fluoride from benzyl chloride in 80% yield and ethyl fluoroacetate from ethyl bromoacetate in 53% yield Methyltnbutylphosphonium fluoride converts 1-bromododecane to a 50 50 mixture of 1-fluorododecane and 1-dodecene Methyltnbutylphosphonium fluoride also quantitatively forms styrene from 1-bromo-1-phenylethane [26] Methyl-tnbutylphosphonium fluonde is the reagent of choice for the conversion of N,N dimethylchloroacetamide to its fluoride, but it is not able to convert chloro-acetonitnle to fluoroacetomtrile Methyltnbutylphosphonium fluoride changes chloromethyl octyl ether to the crude fluoromethyl ether in 66% yield The stereoselectivity of methyltnbutylphosphonium fluoride is illustrated by the reac tions of the 2-tert-butyl-3-chlorooxiranes [27] (Table 2)... 

In l-chloro-2-fluoroacenaphthene [58] and in 2,3-dihalo-2,3-dihydrobenzofuran [59, 60], potassium t rt-butoxide eliminates hydrogen fluonde in preference to hydrogen chloride. trares-2-Chloro-3-fluoro-2,3-dihydrobenzofuran loses hydrogen fluoride quantitatively on treatment with sodamide in tert-butyl alcohol [60] (equation 29). 

O-isopropylidene derivative (57) must exist in pyridine solution in a conformation which favors anhydro-ring formation rather than elimination. Considerable degradation occurred when the 5-iodo derivative (63) was treated with silver fluoride in pyridine (36). The products, which were isolated in small yield, were identified as thymine and l-[2-(5-methylfuryl)]-thymine (65). This same compound (65) was formed in high yield when the 5 -mesylate 64 was treated with potassium tert-hx Xy -ate in dimethyl sulfoxide (16). The formation of 65 from 63 or 64 clearly involves the rearrangement of an intermediate 2, 4 -diene. In a different approach to the problem of introducing terminal unsaturation into pento-furanoid nucleosides, Robins and co-workers (32,37) have employed mild base catalyzed E2 elimination reactions. Thus, treatment of the 5 -tosylate (59) with potassium tert-butylate in tert-butyl alcohol afforded a high yield of the 4 -ene (60) (37). This reaction may proceed via the 2,5 ... 

Doyle and Bryker (1979) reported high yields of arenediazonium tetrafluoroborates when aromatic amines were reacted with tert-butyl nitrite and trifluoroboro etherate in CH2C12. It is likely that nitrosyl fluoride is formed as nitrosating reagent by fluoride-alkoxy exchange. 

Neither methyl nor ethyl fluoride gave the corresponding cations when treated with SbFs. At low temperatures, methyl fluoride gave chiefly the methylated sulfur dioxide salt, (CH3OSO) ShF while ethyl fluoride rapidly formed the rert-butyl and ferf-hexyl cations by addition of the initially formed ethyl cation to ethylene molecules also formed ° At room temperature, methyl fluoride also gave the tert-butyl cation. In accord with the stability order, hydride ion is abstracted from alkanes by super acid most readily from tertiary and least readily from primary positions. 

Enantioselective allylations of a-nitro ketones and a-nitro esters with allyl acetates are carried out in the presence of 2 equiv of alkali metal fluorides (KF, RbF, CsF) and 1 mol% palladium catalysts prepared in situ from Pd2(dba)3-CHC13 and chiral phosphine ligands. Moderate enantio-selectivity (ca 50% ee) is reported for allylation of cx-nitroketones (Eq. 5.60). The highest selectivity (80% ee) is observed for allylation of the reaction of tert-butyl ester (Eq. 5.61).93... 

Vinylsilane to copper transmetallation has entered the literature,93 93a,93b and a system suitable for catalytic asymmetric addition of vinylsilanes to aldehydes was developed (Scheme 24).94 A copper(l) fluoride or alkoxide is necessary to initiate transmetallation, and the work employs a copper(ll) fluoride salt as a pre-catalyst, presumably reduced in situ by excess phosphine ligand. The use of a bis-phosphine was found crucial for reactivity of the vinylcopper species, which ordinarily would not be regarded as good nucleophiles for addition to aldehydes. The highly tailored 5,5 -bis(di(3,5-di-tert-butyl-4-methoxyphenyl)phosphino-4,4 -bis(benzodioxolyl) (DTBM-SEGPHOS) (see Scheme 24) was found to provide the best results, and the use of alkoxysilanes is required. Functional group tolerance has not been adequately addressed, but the method does appear encouraging as a way to activate vinylsilanes for use as nucleophiles. 

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