Cyclohexyl iodide

Methyl fluonde Pentyl chloride 1 Ethylbutyl bromide Cyclohexyl iodide... 

Fig. 3.6. NMR spectrum of cyclohexyl iodide at —80°C. Only the lowest-field signals are shown (100-MHz spectrum). [Reproduced from J Am. Chem. Soc. 91 344 (1969) by permission of the American Chemical Society.]...

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... 

Pyridine is added to neutralize small amounts of hydrogen iodide, which is often present in iodotrimethylsilane as a result of hydrolysis by contact with moisture. The amount of by-products, including cyclohexyl iodide, is reduced by the presence of pyridine. Hindered pyridine bases such as 2,6-di-terf-butyl-4-methylpyridine" have also been used for this purpose by the submitters. The pyridine bases do not appear to react with iodotrimethylsilane. 

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. 

Iodoalkane, oxirane iodoreduction to, cyclohexyl iodide, 136 4-Iodobenzyloxytriethylsilane, ether reduction, 126 Ionic hydrogenation ... 

N-Boc-cyclododecylamine, reductive Boc protection, 128 Oxirane, iodoalkane iodoreduction, cyclohexyl iodide, 136 Oxonium ions, alkene to alkane... 

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... 

Cyclohexyl iodide reacts faster in Sn2 displacements than equatorial iodide, reason ... 

Benzoxazinones 141 and 143 have been reacted in a reductive radical alkylation using triethylborane as the alkyl radical source <2004SL2597>. Triethylborane could also be used in catalytic amount with isopropyl, tert-h xVj, or cyclohexyl iodide as the alkylating agent. Zinc with copper iodide could also he used as initiator (Scheme 8). 

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. 

The addition of functionalized alkyl radicals to protonated heteroaromatics was more difficult (because the radicals could not be generated by H-atom abstraction), but a recent development holds promise to resolve this problem. Generation of a methyl radical in the presence of an alkyl iodide sets up a relatively rapid equilibrium as indicated in Scheme 85. This equilibrium will favor any more highly substituted alkyl radical over methyl, and further, this latter radical will be significantly more nucleophilic. Thus when methyl radicals are generated in the presence of cyclohexyl iodide and a protonated quinaldine, die... 

RX. n-butyl bromide n-dodecanyl iodide cyclohexyl iodide ethyl bromo acetate methyl 2,3-di-O-acetyl-4-O-benzoyl-6-bromo-6-deoxy-ot-D-glucopyranoside methyl 2,3,4-tri-0-acetyl-6-deoxy-6-iodo-0 -D glucopyranoside l,2 3,4-di-0-isopropylidene-6-deoxy-6-iodo-a-D-galactopyranose methyl 2(R)-[(tert-butoxycarbonyl)amino]-3-iodo-propionate cyclic bis(trifluoromethyl)oxazolidinone bromide. 

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. 

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. 

---