Iodocyclohexane

The carbonylation of some alkyl halides such as iodocyclohexane (911) can be carried out under neutral conditions in the presence of N,N,N.N-tetre,-methylurea (TMU), which is a neutral compound, but catches generated hydrogen halide. Molecular sieves (MS-4A) are used for the same pur-pose[768]. Very reactive ethyl 3-iodobutyrate (912) is carbonylated to give ethyl methylsuccinate (913) in the presence of TMU. The expected elimination of HI to form crotonate, followed by carbonylation, does not occur. 

Alkyl ketones can be prepared by the carbonylation of alkyl iodides in the presence of organoboranes. The carbonylation of iodocyclohexane with 9-octyl-9-BBN at 1 atm gives cyclohexyl octyl ketone in 65% yield[386]. This reaction is treated in Section 1.1.3.3. Methyl o-methylacetoacetate (919) is obtained by the reaction of the 2-bromopropionate 918, which has a /9-hydrogen, with CO and Me4Sn. PhjAs as a ligand gives better results than Ph3P[771]. 

The chloro- and bromo-cyclohexane inclusion compounds have been extensively examined by infrared (4000-30 cm-1) spectroscopy65-68 and by Raman (< 1000 cm-1) spectroscopy 69). In the canals both guests are found to exist exclusively in the chair conformation with an axial halogen substituent, while iodocyclohexane 65, 68,69) acj0pts both axial and equatorial conformations in the canal. These results should be contrasted with the familiar situation in the liquid phase where the equatorial arrangement is the lowest energy conformer and is present to the extent of about 65-70% at room temperature. 

An interesting hydroiodination reaction occurs when a mixture of cyclohexene and triethylsilane in dichloromethane is treated with a mixture of bis(pyridine) iodonium tetrafluoroborate and tetrafluoroboric acid in diethyl ether (Eq. 125). A 50% yield of iodocyclohexane is produced after one hour at 20°.268... 

IODOCYCLOHEXANE, 51, 45 IODODURENE, 51, 94. trans-6-Iodoisocyandtes, general synthesis from olefins with iodine isocyanate, 51, 114... 

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

B. Iodocyclohexane. A 500-ml. two-necked round-bottomed flask is fitted with a reflux condenser to which is attached a calcium chloride drying tube. To the flask are added 124 g. (107 ml., 0.4 mole) of triphenyl phosphite and 85 g. (37 ml.,... 

Similarly, the oxidation of iodocyclohexane by DMD under a nitrogen-gas atmosphere leads to the iodohydrin and diol as unexpected products (equation 24). The iodohydrin, formed as the major product, clearly reveals that hypoiodous acid (HOI) is generated in situ, which adds to the liberated cyclohexene. Indeed, when methyl iodide (Mel) is oxidized by DMD at subambient temperature in the presence of cyclohexene, the corresponding iodohydrin is obtained in very good yield The latter method may be utilized for the preparation of allylic alcohols with a vinylic iodo functional group from allenes (equation 25) . ... 

In a mixture of 70% HF/ pyridine (50 mL) and sulfolane (30 mL) was dissolved I2 (7.2 g, 0.03 mol). Cyclohexene (2.6 g, 0.03 mol) dissolved in sulfolane (30 mL) was then added over 10 min at rt. The mixture was stirred for 20 min and was then poured into ice water and extracted with Et20. The ethereal layer was washed with H20. aq NaHC03, H20 again and dried (Na2S04). After evaporation of Et20 and unreacted cyclohexene, pure t-fluoro-2-iodocyclohexane was obtained by distillation under reduced pressure yield 4.9 g (60%) bp 73-75 C/10 Torr. 

When cyclohexene (5) is treated with bis(pyridine)iodonium tetrafluoroborate (Ipy2BF4, 6) in the presence of tetrafluoroboric acid in dichloromethane, irans- -fluoro-2-iodocyclohexane (7) is obtained in 89% yield, with the tetrafluoroborate counter anion acting as the source of fluoride ion.59 60... 

A more recent, direct, simple iodination was also disclosed using periluoroalkyl iodides.289 When cyclohexane, for example, is refluxed with C4F9I in acetic acid in the presence of catalytic amounts of tert-BuOOH and Fe(OAc)j, iodocyclohexane is formed in 70% yield. Mechanistic consideration of this Gif-Barton catalysis is given in Section 9.6.1. 

Diodopropane - from 40 g (38 ml, 0.525 mol) of propane-1,3-diol (trimethylene glycol). Proceed as for iodocyclohexane stop heating as soon as all the iodine has been added. (B.p. 88-89 °C/6 mmHg). 

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