Hexane, 1,6-dibromo

The above product (24 g, 0.067 mol) was dissolved in 90 10 dioxane-water (300 ml) and sodium borohydride (92.5 g, 0.067 mol) was added. The mixture was refluxed for 4h. The cooled solution was poured into 0.1 N HCl (1.11). A solid precipitated and was collected by filtration, dried and recrystallized from ether hexane to give 6,7-dibromo-4-methoxyindole (18.5 g, 90%). 

The only known reaction of a furan with a dihalocarbene is that recently reported between benzofuran and dichlorocarbene in hexane at 0°. The initial adduct (7) could not be isolated but on hydrolysis gave the ring-expanded product 8, possibly via 9, in 15% yield. Benzothiophene was recovered in 92% yield under the same conditions. 2,5-Dihydrofuran reacted with dichloro- and dibromo-carbene to give the products of allylic insertion, 2-dihalogenomethyl-2,5-dihydrofuran, as well as the normal addition products. ... 

Cyclohexadiene has been prepared by dehydration of cyclohexen-3-ol,3 by pyrolysis at 540° of the diacetate of cyclohexane-1,2-diol,4 by dehydrobromination with quinoline of 3-hromocyclohexene,6 by treating the ethyl ether of cyclohexen-3-ol with potassium bisulfatc,6 7 by heating cyclohexene oxide with phthalic anhydride,8 by treating cyclohexane-1,2-diol with concentrated sulfuric acid,9 by treatment of 1,2-dibromocyclo-hexane with tributylamine,10 with sodium hydroxide in ethylene glycol,10 and with quinoline,6 and by treatment of 3,6-dibromo-cyclohexene with sodium.6... 

A mixture of 2,3-dibromo-l,4-diheptylnaphthalene (3.6 g, 7.5 mmol) and CuCN (4 g, 44 mmol) in DMF (20 mL) was heated under reflux for 6 h. Coned NH, (80 mL) was added and air was bubbled through the suspension for 10 h. The precipitate was filtered and extracted with CHC13. The solvent was evaporated and the residue recrystallized (hexane) to obtain a pale-brown powder yield 800 mg (36%) mp 101-103 C. 

Thermal rearrangement of trans-l,2-dibromo compounds is known in the literature (refs. 6-10). In all case studies only one pair of bromine in each organic molecular was studied. Bellucci (ref. 10), for example, studied the kinetics of such trans-l,2-cyclo alkanes as cyclopentane, hexane, octane, etc. The intermediates suggested as an explanation for the experimental results are bromonium bromide I in polar solvents and four center transition state II in non-polar solvents. 

Scheme 6.74 Generation of 1-oxa-2,3-cyclohexadiene (351) from 6,6-dibromo-2-oxabicyclo[3.1.0]hexane (350), dimerization of351 and its trapping by styrene.

Scheme 6.82 Treatment of 6,6-dibromo-3-thiabicyclo[3.1.0]hexane (398) with methyllithium, trapping ofthe resulting l-thia-3,4-cyclo-hexadiene (399) by styrene, 1,3-butadiene and furan and the structure ofthe dimer404 of 399.

Azatricyclo[2.2.1.02 6]hept-7-yl perchlorate, 2368 f Azetidine, 1255 Benzvalene, 2289 Bicyclo[2.1.0]pent-2-ene, 1856 2-/ert-Butyl-3-phenyloxaziridine, 3406 3 -Chloro-1,3 -diphenyleyclopropene, 3679 l-Chloro-2,3-di(2-thienyl)cyclopropenium perchlorate, 3388 Cyanocyclopropane, 1463 f Cyclopropane, 1197 f Cyclopropyl methyl ether, 1608 2,3 5,6-Dibenzobicyclo[3.3.0]hexane, 3633 3,5 -Dibromo-7-bromomethy lene-7,7a-dihy dro-1,1 -dimethyl-1H-azirino[l,2-a]indole, 3474 2.2 -Di-tert-butyl-3.3 -bioxaziridinc, 3359 Dicyclopropyldiazomethane, 2824 l,4-Dihydrodicyclopropa[ >, g]naphthalene, 3452 iV-Dimethylethyl-3,3-dinitroazetidine, 2848 Dinitrogen pentaoxide, Strained ring heterocycles, 4748 f 1,2-Epoxybutane, 1609 f Ethyl cyclopropanecarboxylate, 2437 2,2 -(l,2-Ethylenebis)3-phenyloxaziridine, 3707 f Methylcyclopropane, 1581 f Methyl cyclopropanecarboxylate, 1917 f Oxetane, 1222... 

A. (1,3-Dibromo-3,3-difluoropropyl)trimethylsilane (Note 1). A 250-mL pressure tube (Note 2) equipped with a magnetic stirring bar is charged with vinyltrimethylsilane (20 g, 30.8 mL, 0.20 mol), ethanolamine (6.11 g, 6.04 mL, 0.10 mol), dibromodifluoromethane (83.9 g, 36.5 mL, 0.4 mol), copper(l) chloride (0.18 g, 1.8 mmol), and tert-butyl alcohol (15 mL) (Notes 3 and 4). The tube is sealed and stirred for 20 hr in an oil bath at 90°C (Note 5). The reaction mixture is combined with that from another run at the same scale and diluted with 40 mL of hexane (the mixture separates into a cloudy supernatant and a brown resin). The hexane layer is... 

For the determination of 1,2-dibromoethane (EDB) and l,2-dibromo-3-chloropro-pane (DBCP) in water by hexane microextraction and GC... 

Brominated Monomer/Oligomer Mixtures from IV (V). The brominated sulfone monomer/oligomer mixtures were preparedby two different methods. Method A A mixture of pyridine (70mL), IV (11.5 mmol), dibromobenzene (26.96g, 115 mmol), anhydrous potassium carbonate (7.94g, 57.5 mmol) and cuprous iodide (0.13g, 0.7 mmol) was heated at reflux under nitrogen for 24h. After cooling to room temperature, the reaction mixture was acidified with IN HC1 and the aqueous solution extracted with ether. The organic phase was reduced in volume to a brown gum which was washed several times with hexane and then dried to give a 75-95% yield of the dibromo product. 

Hexene, s-Diethylethylene or y-Hexylene. C2H5CH CHC2H5 mw 84.16 liq, bp 70°, d 0.693 at 20°. Prepd by reacting 3,4-dibromo-hexane with Zn dust or by partial hydrogenation of 3-hexyne over Raney nickel Refs 1) Beil 1, [192], 806 <837>... 

The step 1 product (0.004 mol) and potassium r-butoxide (0.008 mol) were heated to 110°C in a solvent mixture of 25 ml DMAc and 10 ml hexane overnight in a flask containing a Dean-Stark apparatus. After hexane was removed, the mixture was cooled to ambient temperature and treated with trans-l,4-dibromo-2-butene (0.004 mol) and then stirred at ambient temperature for 48 hours. The mixture was then poured into 800 ml of water and a white solid isolated that was air dried and the product isolated in 91% yield. 

Dibromo-biphenyl-2,2 -diamine (14.6 mmol) was suspended in 16 ml of 16% aqueous hydrochloric acid at 0°C and treated with sodium nitrite (31.9 mmol) while maintaining the temperature at 0°C. After an additional hour of stirring 5 ml of KI solution (30.1 mmol) was added dropwise to the reaction mixture at — 10°C. The reaction mixture was slowly warmed to ambient temperature and then heated to 50°C for 2 hours. It was then cooled to ambient temperature and basified with 90 ml of 10% aqueous NaOH and the product extracted into diethyl ether. The organic layer was washed with brine, dried with anhydrous MgSC>4, and concentrated. After purification by chromatography using hexane 1.4 g of product was isolated as an off-white solid, mp = 89°C. 

The successful application of the Doering-Moore-Skattebol reaction to the preparation of relatively small-ring heteroorganic cycloallenes is of recent origin. A specific example is provided by 6,6-dichloro- and 6,6-dibromo-3-oxa-bicyclo-[3.1.0]hexane, respectively, which yield l-oxa-3,4-cyclohexadiene when treated with n-butyllithium at low temperatures. The formation of the allene was proven by various trapping experiments [89],... 

Reaction of a mixture of cis- and rrazz.v-l,l-dibromo-4,5-dimethylspiro[2.3]hexane with methyl-lithium gave a mixture of cis- and nm -2,3-dimethyl-l-vinylidenecyclobutane (3).48... 

Preparation of spiro[2.3]hexanes is possible by the addition of methylene or a methylene equivalent to an exocyclic C —C double bond. Generally, the Simmons Smith reaction is used (see Section l.A.1.2.1.), but formation of carbenes from nitroso compounds can also be used.73-75,333 The 1,1-dihalo derivative can be prepared by phase-transfer-catalyzed reactions.48 For example, reaction of a mixture of cis- and trans-1,2-dimethyl-3-methylenecyclobutane with dibromo-carbene gave a mixture of cis- and lrans-1,1-dibromo-4,5-dimcthylspiro[2.3]hexanc (2).48... 

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