Cyclohexyl iodide, reaction

In a variation of the scheme above, alkylation of p-hydroxy-benzoic acid with cyclohexyl iodide affords the cyclohexyl ether, 55. (Under alkaline reaction conditions, the ester formed concurrently does not survive the reaction.) Acylation of the acid chloride obtained from 55 with the preformed side chain (56) gives cyclomethycaine (57). ... 

In addition to simple halides, the method was used to prepare chol-esteryl iodide (30%) and cyclohexyl iodide (34%) from the corresponding alcohols, thus demonstrating the applicability of the reaction to cyclic secondary alcohols. An early adaptation to carbohydrates was reported by Lee and El Sawi (75). They claimed that treatment of l,2 5,6-di-0-isopropylidene-D-glucofuranose (49) with triphenylphosphite methiodide... 

When an insufficient amount of iodotrimethylsilane was used by the submitters, cyclohexyl methyl ether remained at the end of the reaction and was eluted from the silica gel column before cyclohexanol. When present in the crude product, cyclohexyl iodide was also eluted from the column before cyclohexanol. 

In the initial work, the reaction of cyclohexyl iodide or isocyanide with a variety of alkenes mediated by (TMS)3SiH was tested, in order to find out the... 

The simple addition reaction in Scheme 19 illustrates how the notation is used. Ester (1) can be dissected into synthons (2), (3) and (4). Synthons for radical precursors (pro-radicals) possess radical sites ( ) A reagent that is an appropriate radical precursor for the cyclohexyl radical, such as cyclohexyl iodide, is the actual equivalent of synthon (2). By nature, alkene acceptors have one site that reacts with a radical ( ) and one adjacent radical site ( ) that is created upon addition of a radical. Ethyl acrylate is a reagent that is equivalent to synthon (3). Atom or group donors are represented as sites that react with radicals ( ) Tributyltin hydride is a reagent equivalent of (4). In practice, such analysis will usually focus on carbon-carbon bond forming reactions and the atom transfer step may be omitted in the notation for simplicity. 

An interesting method for the preparation of epoxides using radical methodology has been reported [95AJC233]. Addition of cyclohexyl iodide 1 under reductive or non reductive conditions to ethyl t-butylperoxymethylpropenoate 2 at refluxing temperatures furnished the epoxide 4 in moderate yield. The reaction proceeds through an intramolecular homolytic displacement. 

The second key to success in making sure that the alkyl radical behaves well is to use a reactive radical trap. In fact, this is a major limitation of intermolecular radical carbon-carbon bond-forming reactions for the trapping of alkyl radicals only electrophilic alkenes (attached to electron-withdrawing groups such as -CN, -CC Me, -COMe) will do. This is a limitation, but nonetheless, cyclohexyl iodide adds to all these alkenes with the yields shown and the rate of addition to most of these alkenes is 103 to 104 times that of addition to 1-hexene. 

An alternative method of preparation of the cyclohexyl radical which has been used is by the reaction of the phenyl radical (prepared from phenyl iodide and sodium) with a matrix of cyclohexane. Clearly the amount of cyclohexane formed by the disproportionation reaction cannot be measured. However, the amount of benzene, formed in the initial abstraction reaction, is equal to that of the cyclohexyl radicals and thus also to the total amount of products formed by the cyclohexyl termination reactions. Thus a mass balance can be made and values of k jkc (Table 9) calculated on the same basis as before (Fig. 20). An upper limit of the value of k jk can be obtained from these experiments on the assumption that no side reactions occur. The material balance gives... 

A related selectivity question is answered with the reactions of (ii)-geranyl bromide (eqnation 135). Complexation gives a noncrystalline residne that conples with cyclohexyl iodide on heating in DMF, bnt the coupled product shows... 

Naito has also described analogous tandem radical addition-cyclization processes under iodine atom-transfer reaction conditions [16,32], Treatment of 186 with z-PrI (30 eq.) and triethylborane (3x3 eq.) in toluene at 100 °C gave, after cleavage from the resin, the desired lactam product 190 in 69% yield (Scheme 46). Similar reactions involving cyclohexyl iodide, cyclopentyl iodide, and butyl iodide were also reported as well as the reaction with ethyl radical from triethylborane [16,32], The relative stereochemistry of the products was not discussed. 

Dialkyl telluriums, diaryl telluriums, and alkyl aryl telluriums are converted to triorgano telluronium salts on reaction with alkyl halides. These alkylations proceed easily with methyl, ethyl, and propyl iodide, allyl bromide cyclohexyl iodide, ethyl bromoace-tate , and even bromobenzene and iodobenzene -... 

The slowness of the reaction at room temperature is probably due to the preferential adsorption and/or reduction of crotononitrile on nickel boride, which hinders the radical formation reaction of cyclohexyl iodide at room temperature. Cyclohexyl iodide is quantitatively reduced to cyclohexane by BER-Ni2B (cat.) within 1 h at room temperature in the absence of excess crotononitrile [12a]. 

Exposure of 14 (m = 3, R = rcrf-Bu) to cyclohexyl iodide, allyltributylstannane, and AIBN leads to a macrocycle 15 with two new stereogenic centers. The allyl group provides additional functionality for further transformations and also creates a new stereocenter in the process. In order to effect the desired macrocyclization, addition of the first-formed radical to the proximal acrylamide moiety must be faster than addition to the chain transfer agent allyltributylstannane, a requirement that can be fulfilled under appropriate reaction conditions. Premature chain transfer in this particular system, under conditions that discourage bimolecular reaction between two templates, leads to two simple n = 1 products (vide infra). 

Scheme 8-6 Telomer distribution for reaction of template 14 (/n = 3, R=ferf-Bu) with allyltribu-tylstannane and cyclohexyl iodide.

A simple template-free methyl acrylate telomerization was conducted using the cyclohexyl iodide/allyltributyltin system in order to identify retention times for the telomers 26 from the ACT reactions. Telomerization of methyl acrylate (900 mM) with 120 mM cyclohexyl iodide and 300 mM allyltributyltin gave 27% of the n=4 telomers. Scheme 8-10. Under the best GC conditions found, only four different n=4 telomers, out of a possible 16, were observed in this product mixture. This experiment gives a baseline value for telomer distribution obtained without the use of a template. It is clear that simple template-free telomerization is not useful for the preparation of an oligomer of a specific length. 

It should be noted that the ACT sequence and the standard telomer assay were employed to study oligoselectivity with this template and thus the products analyzed are the same methyl acrylate telomers identified in the previous studies. The ACT reaction of 40 under standard conditions with cyclohexyl iodide and allyltributyltin (2.5 /80V200 "), without the aid of a counter-ion, showed interesting results. The product histogram obtained with 40 after telomer assay is presented in Scheme 8-15. 

Relatively non-toxic tris(trimethylsilyl)silane performs the same function as Bu3SnH in standard radical-chain reactions, such as hydrocarbon synthesis from ethylene derivs. and iodides. E A mixture of cyclohexyl iodide, acrylonitrile, and 1.2 eqs. tris(trimethylsilyl)silane in toluene heated at 70-90° for 4-5 h in the presence of a little AIBN product. Y 90%. Regioselectivity may also be enhanced, and reaction times... 

Would you expect the replacement of cyclohexyl bromide with cyclohexyl iodide to result in a decrease, increase, or no change in the rate of the reaction Explain. 

WORKED PROBLEM 7.9 The axial cyclohexyl iodide shown below reacts more quickly in Sn2 displacements than the equatorial cyclohexyl iodide. Draw the transition states for displacement of iodide from axial cyclohexyl iodide by iodide ion and for the analogous reaction of equatorial cyclohexyl iodide. What is the relation between these transition states Why does the axial iodo compound react faster than the equatorial compound Caution Hard, tricky question. 

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