Hexane 2,4-dibromo-3 methyl

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... 

A useful one-carbon ring-expansion reaction which has been developed involves treatment of l-(dibromomethyl)-cycloalkan-l-ols with n-butyl-lithium in hexane to give the ring-expanded ketones, usually in excellent yield e.g. l-(dibromomethyl)-cyclododecan-l-ol, which was obtained by treating cyclododecanone with dibromo-methyl-lithium, gave cyclotridecanone in 89% isolated yield. ... 

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... 

Reductive dehalogenation with tin hydrides can be carried out without interference of a number of functional groups. However, a C-C double bond in a 1,5 relationship to the intermediate cyelopropyl radical can function as a trap and result in formation of bicyclo[3.1.0]hexane derivatives. Thus, treatment of l,l-dibromo-2-(but-3-enyl)cyclopropane with tributyltin hydride afforded a 15 85 mixture of l-bromo-2-(but-3-enyl)cyclopropane (13) and 1-bromo-2-methyl-bicyclo[3.1.0]hexane (12). Under similar conditions l-bromo-2,8,8-trimethyltricyclo-[3.2.1.0 ]octan-3-one (15) was obtained in 6% yield from an isomeric mixture of 7,7-dibromo-4-isopropenyl-l-methylbicyclo[4.1.0]hept-2-one the main product, isolated in 86% yield, was an isomerie mixture of 7-bromo-4-isopropenyl-l-methylbicyclo[4.1.0]hept-2-one (14). ... 

To a solution of 0.015 mmol aluminum catalyst with (/ )-6,6 -dibromo-3,3 -bis (diphenylphosphinoylmethyl)-2,2 -dihydroxy-l,l -binaphthyl as ligand in CH2CI2 was added 0.6 mmol l-methyl-isoquinoUne in 2.25 mL CH2CI2, followed by 160 ixL TMSCN (1.2 mmol) and 91.8 fiL vinyl chloroformate (1.08 mmol) at —60°C. After 48 h, the reaction was quenched by 5% NH3 aqueous solution, and extracted with EtOAc. Upon removal of solvent under reduced pressure, the reside was purified by column chromatography using hexane/EtOAc as the eluent to afford 91% (+)-l-cyano-l-methyl-l,2-dihydroisoquinoline-2-carboxylic acid vinyl ester as a colorless oil, with 84% e.e. as determined by chiral HPLC analysis. 

A 20%-soln. of butyllithium in hexane added drop wise with toluene-liq. Ng-cool-ing at -95° to a soln. of 9,9-dibromo-c/5 -bicyclo[6.1.0]nonane in dry tetrahydro-furan, stirred 10 min., methyl iodide added in 1 portion, and after 1 hr. gradually warmed to 0° 9-cj o-bromo-9-endo-methyl-c/ -bicyclo[6.1.0]nonane. Y 70%. F. e., also formation of cyclic allenes (cf. Synth. Meth. 17, 959 21, 734) s. H. J. J. Loozen et al., J. Org. Chem. 41, 2965 (1976) cf. Synth. Meth. 24, 664 suppl. 31. 

One-pot process. An ethereal soln. of l,l-dibromo-2-phenylcyclopropane added drop wise at -40° to Li-di-n-butylcuprate prepared by treatment of n-butyllithium in hexane with an ethereal suspension of Cul at -40°, warmed to -20° during 1 hr., treated with excess methyl iodide, and allowed to warm to room temp, during 15 hrs. l-n-butyl-l-methyl-2-phenylcyclopropane. Y ca. 100%. Stereospecificity and f. e. s. Kitatani, T. Hiyama, and H. Nozaki, Am. Soc. 98, 2362 (1976) Bull. Chem. Soc. Japan 50, 1600 (1977). 

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