Cyclopentyl chloride, reaction

Propane and cyclopentane give isopropyl chloride and cyclopentyl chloride, respectively, whereas isobutane is transformed to ferf-butyl chloride under the same reaction conditions (yields are 69%, 74%, and 76%, respectively). Neopentane undergoes isomerization to yield 2-chloro-2-butane (88%). When saturated, hydrocarbons were allowed to react with methylene bromide and SbF5 bromoalkanes were obtained in comparable yields (64-75%). Formation of the halogenated product can be best explained by the mechanistic pathway (I) depicted in Scheme 5.55. Since SbF5 always contains some HF, mechanism (II) may also contribute to product formation (Scheme 5.55). 

Cyclopentyl chloride (79) reacts under irradiation with Ph2P ions to give product 80. This reaction was almost completely inhibited by p-DNB (equation 65)151. 

The main product, cyclopentyldichlorosilane, can be explained by the reaction of one equivalent of silicon with one equivalent of cyclopentyl chloride and hydrogen chloride. The hydrogen chloride used for the reaction should have been formed by the decomposition of cyclopentyl chloride. 

Table 10 Relative Rates of Reaction of Cyclopentyl Bromide and Cyclopentyl Chloride with Magnesium in Several Solvents...

Further work [8IQ, which demonstrated that the rates of reaction of cyclopentyl bromide with magnesium fit the kinetic features of a transport-limited heterogeneous reaction, was based on two sets of experiments. First, the relative rates of reaction of cyclopentyl bromide and cyclopentyl chloride with magnesium in solvents of different viscosities [8If] were examined by applying the constant-surface kinetics technique. The results are summarized in Table 10. These demonstrate that the relative rates of reaction of cyclopentyl bromide with magnesium in a series of solvents were proportional to the inverse of the solvent shear viscosity whereas the reaction of cyclopentyi chloride... 

To test these alternative hypotheses, a tremendous amount of work has been done, by Brown and by others. For example, camphene hydrochloride is known to undergo ethanolysis 6000 times as fast as rer/-butyl chloride, and this had been attributed to anchimeric assistance with formation of a bridged ion. Brown pointed out that the wrong standard for comparison had been chosen. He showed that a number of substituted (3°) cyclopentyl chlorides (examine the structure of camphene hydrochloride closely) also react much faster than rerr-butyl chloride. He attributed these fast reactions—including that of camphene hydrochloride—to relief of steric strain. On ionization, chloride ion is lost and the methyl group on the ap hybridized carbon moves into the plane of the ring four non-bonded interactions thus disappear, two for chlorine and two for methyl. For certain systems at least, it became clear that one need not invoke a nonclassical ion to account for the facts. 

Cyclohexyl and cyclopentyl bromides underwent rapid reaction with SbCl, in CCl to give vicinal trans- bromochlorides in high yield. The insertion compound of SbClj in graphite, Cj SbClj, was also employed with the above substrates, where the major products were cyclohexyl and cyclopentyl chlorides ca. 60 %) and smaller amounts (18—35%) of vicinal trans-bromochlorides. Cyclohexyl chloride was obtained in 86% and 22% yield from the iodide and tosylate. 

An important difference between the theories behind Figs. 1 and 2 is that one expects from the former that the solvolysis of camphene hydrochloride (12) would be accelerated because it should lead to a synartetic ion (enter and leave from the right-hand side of Fig. 1), whereas it would not be accelerated if the latter theory is correct. Ethanolysis of camphene hydrochloride (12) occurs about 6000 times faster than that of r-butyl chloride but only 2.5 times faster than that of 1,2,2,5,5-pentamethyl cyclopentyl chloride (13). Hence the decision as to whether the ethanolysis of (4) is accelerated depends on which model reaction is chosen for the nonassisted... 

Apparatus and procedure Closely similar to the preparation of tert.-Ci,H3MgCl, cyclohexyl-MgCl and cyclopentyl-MgCl (see Exp. 2). The yield (estimated from the results obtained from reactions with this reagent) is at least 90%. Here, too, it is essential to use M-butyl chloride which is free from butyl alcohol. 

Weinreb et al86 have also studied the participation of allenes in imino-ene and carbonyl-ene reactions. Gycloisomerization of imine 133 in the presence of stannic chloride gave exclusively the m-substituted cyclopentyl isomer 135 (Scheme 27). The thermal imino-ene reaction of 136 was equally effective. More highly substituted... 

The A-trimethylsilylimines 68 (R = t-Bu, Ph, 2-MeCgH4 or 2-BrC6H4), which are prepared by the reaction of non-enolizable aldehydes with lithium bis(trimethylsilyl)amide, followed by trimethylsilyl chloride, undergo pinacolic coupling induced by NbCLt 2THF to yield the vicinal diamines 69 as mixtures of dl- and meso-isomers, in which the former predominate. Another method for the preparation of 1,2-diamines is by the combined action of the niobium tetrachloride/tetrahydrofuran complex and tributyltin hydride on cyanides RCN (R = /-Hu. Ph, cyclopentyl or pcnt-4-en-l-yl) (equation 32)82. 

However, the hydroxyl group can easily be converted to water, a better leaving group, and this allows the reaction to proceed. One such conversion involves tosyl chloride, and the formation of a tosylate. For example, cyclopentanol reacts with TsCl to form cyclopentyl tosylate, and the corresponding tosylate is reduced conveniently to cyclopentane. 

The isopropyl compound V, (R = Me2CH) has readily been obtained from VI and isopropylmagnesium chloride in ether solution (94) but when R = cyclopentyl, THF has been found to be necessary for effecting the reaction. When R = tert-butyl the Grignard reaction yielded the dimer VII, but the desired V (R = er -butyl) has been obtained... 

Similarly, fused and spiro cyclopropane systems 31 and 33 can also be synthesized by the reaction of appropriate cycloalkenyl cobaloximes 30 and 32 with free radical precursors such as toluenesulfonyl iodide (Scheme 11). The thermal and photochemical reactions of hexenyl cobaloximes 34 with a large excess of CCI4 gives mainly the pentachloroheptane 35 (path A). On the other hand, the photochemical reactions in the presence of low concentration of CCI4 gives mainly the cyclopentyl methyl chloride 36a through homolysis of the C-Co bond followed by cyclization of the hexenyl radical and chlorine atom abstraction (path B). However,... 

The following sequence (equation 6) constitutes a convenient alternative to the conversion of alkyl halides into alkylamines by the Gabriel reaction with potassium phthaUmide. In this one-pot procedure, an alkyl bromide RBr (R = Bu, -Bu, 2-pentyl, 2-octyl, PhCH2CH2, HC=C, PhCH=CHCH2, cyclopentyl, cyclohexyl etc.) is treated with sodium azide in benzene in the presence of tetrabutylammonium bromide under phase-transfer conditions. Triethyl phosphite is then added and the resulting iminophosphorane is decomposed to the alkyl amine hydrochloride by adding benzene and hydrogen chloride. ... 

IIR, 3S, 4S)-3-azido-4-(benzoyloxymethyl)cyclopentyl]-carboxylic acid, 127, obtained in 8 steps from ndo-norbomenyl acetate 126 [184,185] (Fig. 23). The carboxylic acid group of 127 was transformed to the urea 128, which by reaction with 3-methoxy-2-methylacryloyl chloride and cyclization, afforded the carbocyclic 3 -azido-3 -deoxythymidine 123 [184, 185]. 

---