T-butyl iodide

Notice that for SN2 substitution, the alkyl halide came from the less sterically hindered group. For SN1 type reactions, the alkyl halide forms from the fragment of the original molecule that forms the more stable cation. Thus, the reaction of t-butyl ethyl ether with HI gives t-butyl iodide and ethyl alcohol. The following mechanism occurs ... 

Concerning transfer agents involving a C-I bond, for trifluoroiodomethane, the wave length A plays an important role on the telomeric distribution since at A lower than 3000 A only CF3C3F6I was formed whereas at higher wave lengths, the two first telomers were produced [268]. However, the photochemically induced addition of perfluoro-t-butyl iodide to HFP, even at 163 °C was unsuccessful [269],... 

This is a typical SN2 reaction (1) kinetics usually display clean second order (b) when the reagent is chiral, inversion of configuration occurs at the asymmetric carbon (71 ACS 18) when the alkylating reagent is tertiary (t-butyl iodide) or even secondary (i-Pr iodide), E2 elimination competes with aliphatic substitution (55JA1715 76AJC1745). 

The photolysis of aromatic species with tetranitromethane in perfluoro alcohol solvent has been studied, in which the radical cations were observed by EPR spectroscopy. " Photo-stimulated reaction of 1- and 2-haloadamantanes and 1,2- and 1,3-dihaloadamantanes with various carbanionic nucleophiles afforded products rationalized through an 5rn 1 mechanism. Photolysis of the cycloadduct formed between a fimctionalized derivative of Ceo and diazomethane has been shown to afford a pair of ring-opened structures (125) and (126) via a proposed biradical intermediate (127) (Scheme 19). The UV-photolytic fragments of t-butyl iodide (T and t-Bu ) have been ionized by resonance-enhanced multiphoton ionization for TOP mass spectro-metric analysis. A two-dimensional position-sensitive detector provided angular distribution and translational energy data. 

On treatment with HI, the ether is protonated. This oxonium ion cleaves readily to give t-butyl alcohol and the relatively stable r-butyl carbocation. Iodide ion adds to the carbocation, and the alcohol reacts with HI both give t-butyl iodide. 

Step A corresponds to a direct unimolecular elimination of hydrogen iodide and Step B to a concerted mechanism for which the activation energy exactly equals the overall endothermicity. These steps are followed by the rapid reaction of the alkyl iodide with hydrogen iodide such that the latter is kept at a low stationary state concentration (except presumably in the case of t-butyl iodide). Step A could be rate-determining for the pyrolyses of ethyl - /-propyl, /-butyl and acetyl... 

Another conjugate addition, to the dehydroalanine derivative 38 on solid-phase, was reported by Yim et al. [19], Radical generation using t-butyl iodide and tribu-tyltin hydride afforded only 8% of the desired product, while better results were obtained with organomercurials (Scheme 8). The intermolecular addition of tosyl radicals to unactivated alkene and alkyne 39 has also been reported [20], and the reaction was found to be quite sensitive to solvent. Optimum results were obtained in toluene, although the scope is difficult to gauge with only two examples disclosed. 

The Pet ester is stable to the acidic conditions required to remove the BOC and t-butyl ester groups, to the basic conditions required to remove the Fmoc and Fm groups, and to hydrogenolysis. It is not recommended for use in peptides that contain methionine or histidine, since these are susceptible to alkylation with methyl iodide. 

Materials. Methyl methacrylate was a product of Rohm and Haas, and t-butyl methacrylate was obtained from Polvsciences, Inc. Potassium trimethylsilanolate (PTMS) was obtained from Petrarch Systems, Inc. Anhydrous lithium iodide, trimethylsilyl iodide (TMSI), and n-butyllit.ium (in hexanes) were purchased from Aldrich Chemical Co. 

Hindered di-t-alkylamines RNHBu1 (R = t-Bu, t-octyl or 1-adamantyl) have been synthesized from t-alkylamines as follows. Reaction with peracetic acid gave the nitrosoalkanes RNO, which were treated with t-butyl radicals, generated from t-butylhydrazine and lead(IV) oxide, to yield t-butyloxyhydroxylamines. Reduction with sodium naphthalide in THF gave the products (equation 12). The di-t-alkyl-amines are inert to methyl iodide and dimethyl sulphate but can be alkylated by methyl fluorosulphonate42. 

A substrate screening was also carried out and reported [67]. For both penta- and tetracoordinate complexes the reaction rate and selectivity increased on going from methyl to t-butyl ketone, thus following the steric hindrance and electrophilicity of the substrate. In the comparison between PPEI and APPEI, the former were markedly more selective in both the neutral (Table 4.7) and cationic complexes. An increase in the iodide Ir ratio also had an improving effect on the asymmetric induction for 77a, reaching a maximum 84% ee at [ "] [Ir] = 3. 

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