NEOPENTYL IODIDE

NEOPENTYL IODIDE, 51, 44 Nerol, 54, 70 Neryl chloride, 54, 70 Nickel carbonyl, precautions for handling, 52, 117 reaction with allyl halides,... 

HEXAMETHYLPHOSPHORAMIDE 1-BENZYLINDOLE, 54, 60 ALKYL IODIDES NEOPENTYL IODIDE, IODOCYCLOHEXANE, 51,... 

Monoalkylation of optically active 1-phenylethylamine with benzyl bromide in N,N-dimethylpropyleneurea (249a) at 100 °C in the presence of sodium carbonate gives the enantiomerically pure A-benzyl derivative. Isopropyl iodide and neopentyl iodide behave analogously275. 

A review of aromatic substitution by the 5 rnI reaction has been published. The reactions of enolate ions of 2-acetyl-(147) and 3-acetyl-1-methylpyrroles (148) with aryl iodides and neopentyl iodides under irradiation conditions afforded good yields of substitution products by 5rn1 mechanisms, without the need for initiator. These... 

A. Neopentyl iodide. A 500-ml. two-necked round-bottomed flask is fitted with a reflux condenser to which is attached a calcium chloride drying tube. One hundred thirty-six grams (115 ml., 0.44 mole) of triphenyl phosphite, 35.2 g. (0.4 mole) of neopentyl alcohol, and 85 g. (37 ml., 0.60 mole) of methyl iodide (Note 1) are added to the flask, and a thermometer is inserted that is of sufficient length to extend into the liquid contents of the flask. The mixture is heated under gentle reflux... 

The reaction mixture is distilled under reduced pressure through a 13-cm. Vigreux column. The fraction boiling below 65° (50 mm.) is collected, washed with 50 ml. of water and then with 50-ml. portions of cold IN sodium hydroxide solution until the washings no longer contain phenol (Note 3). The product is washed again with 50 ml. of water, dried over calcium chloride and redistilled. There is obtained 51-60 g. (64-75%) of neopentyl iodide, b.p. 54-55° (55 mm.), n21v 1.4882 (Note 4). 

T.B. Patrick, L. Zhang, Q. Li, Rearrangement and double fluorination in the deiodi-native fluorination of neopentyl iodide with xenon difluoride, J. Fluorine Chem. 102 (2000) 11-15. 

JCS(P1)249>. In an interesting alternative to direct acylation of this heterocycle, Pierini and Rossi examined the photostimulated SrnI reaction of the enolate of 2-acetyl-1-methylpyrrole 36 with haloarenes (e.g., iodobenzene, 37) as well as neopentyl iodides to afford a-substituted acetyl pyrroles 38 <99JOC6487>. 

Another feature of El reactions (and also of SN1 reactions) is the tendency of the initially formed carbocation to rearrange, especially if a more stable car-bocation is formed thereby. For example, the very slow SN1 solvolysis of neopentyl iodide in methanoic acid leads predominantly to 2-methyl-2-butene ... 

Photo-stimulated reactions of neopentyl iodide with several carbanionic nucleophiles have been studied in which inhibition experiments with the TEMPO radical trap suggest the reaction occurs via an SrnI mechanism.76 Comparison of 22 nucleophiles in then. Srn 1 reactions with iodobenzene by Fe(II)- and photo-induction has revealed that both are enhanced by high electron-donation ability of the nucleophile. The radical anion Phl is a key intermediate.77 The SET reactions of perfluoroalkyl iodides have been reviewed.78 Flash photolysis of H2O2 was used to generate HO and 0 radicals which were reacted with a, a. z-trifluorotolucnc (TFT) and 4-fluorotoluene (4FT) and the rate constants calculated.79 The diminished reactivity of TFT towards HO or O with respect to toluene or benzene was consistent with radical addition to the aromatic ring, whilst the reactivity of 4FT was of the same order as electron-deficient toluenes, which favour H abstraction from the aliphatic side-chain. 

Photostimulated, S r k 1 reactions of carbanion nucleophiles in DMSO have been used to advantage in C—C bond formation (Scheme 1).25-27 Thus, good yields of substitution products have been obtained from neopentyl iodide on reaction with enolates of acetophenone and anthrone, but not with the conjugate base of acetone or nitromethane (unless used in conjunction, whereby the former acts as an entrainment agent).25 1,3-Diiodoadamantane forms an intermediate 1-iodo mono substitution product on reaction with potassium enolates of acetophenone and pinacolone and with the anion of nitromethane subsequent fragmentation of the intermediate gives derivatives of 7-methylidenebicyclo[3.3.1]nonene. Reactions of 1,3-dibromo- and 1-bromo-3-chloro-adamantane are less effective.26... 

Baumgartner, M.T., Pierini, A.B. and Rossi, R.A. (1999) Reactions of 2-and 3-acetyl-l-methylpyrrole enolate ions with iodoarenes and neopentyl iodides by the SRn1 mechanism. Journal of Organic Chemistry, 64, 6487-6489. 

As already mentioned, hypervalent iodine reagents are useful for the oxidatively assisted nucleophilic substitution of iodine in iodoalkanes (Section 5.4.2). In this way HTI was used for the preparation of some tosylates. A rearrangement occurred with neopentyl iodide, Me3CCH2I, which was converted into the ester Me2C(OTs)CH2Me (85%) [53]. The most successful application of such reactions for preparative purposes was the functionalization of some iodocubanes and iodohomocubanes, and especially the preparation of their triflates and mesylates from iodosylbenzene-trimethylsilyl triflate and [hydroxy(mesyloxy)iodo]benzene, respectively [54,55]. 

The substitution product was obtained in modest yield when the reaction was performed with PhSe ions153. On the other hand Na2Se, formed in liquid ammonia from Se and Na metals, reacted with neopentyl iodide (97) to give dineopentyl diselenide (100) from oxidation of 98 (equation 73b), together with a small amount of dineopentyl selenide (99) (equation 73 a)155. 

In the reaction of the neopentyl iodide radical probe 108 with lithium propiophenone in HMPA, the O-substituted 109 (66%) and the C-substituted 110 compounds (11%) were... 

Clearly, both spectra are of the tertiary 2-methylbutyl cation and the neopentyl cation never saw the light of day. The reaction is the same rearrangement that you saw in the substitution reaction of neopentyl iodide, but here the rate of rearrangement can be measured and it is extremely fast. Ncopentyl tosylate reacts to form a cation under these conditions about 104 times as fast as ethyl tosylate, even though both tosylates are primary. This massive rate difference shows that if migration of an alkyl group can allow rearrangement to a more stable carbocation, it will happen, and happen rapidly. 

Cyclization of diazonium salts using iodide ion had been well developed by Beckwith s group, but the iodide corresponding to 50 is a secondary neopentyl iodide, which would be impossible to convert by S 2 chemistry into an alcohol. Our efforts to convert similar iodides to acetate esters with silver acetate by S l have also not met with success. Even if such conversions were possible, they would still be much less direct than with the new radical-polar crossover methodology. 

The best results were obtained when aromatic Grignard reagents were employed in the presence of NiCliCdppf). For example, neopentyl iodide (5.37) reacts with 5.35 to give 86% 5.38 in the presence of NiCl2(dppf). 

Organometallic compounds of magnesium, mercury, or lithium have been treated with iodine or bromine to form organic halides. The method has been successful for obtaining neopentyl iodide where other methods have failed (92%). It has been found convenient in the synthesis of 9-iodoanthracene (53%) and certain heterocyclic halides. ... 

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