L-Iodo-3-methylbutane

Cycloheptanes.— The C-1—C-2 bond in -y-thujaplicin is essentially single, Co"-/3-thujaplicin-amine complexes have been described, and thermodynamic data on the U -/3-thujaplicin complex have been calculated. The biomimetic cyclization of the silyl enol ether (191) to karahanaenone (192), using methyl-aluminium bis(trifluoroacetate) is almost quantitative (192) is also synthesized by thermolysis followed by desilylation of the silyl enol ether (193) which is readily available from l-bromo-2-methyl-2-vinylcyclopropane and isobutyraldehyde. Dehalogenation of 3-bromo-l-iodo-3-methylbutan-2-one with Zn-Cu couple on alumina in the presence of isoprene yields (192) and minor amounts of the isomers (194) and (195) however, dehalogenation with Fc2(CO)9 favours (195). Acetolysis of karahanaenol tosylate yields anticipated p-menthane derivatives and no filifolene. ... 

Dissolve 37.5 g (0.25 mol) of dry sodium iodide (1) in 250 ml of dry acetone in a 500-ml flask fitted with a reflux condenser protected by a calcium chloride guard-tube, and add 30.2 g (25 ml, 0.2 mol) of l-bromo-3-methylbutane. A precipitate of sodium bromide soon begins to form leave the reaction mixture at room temperature for 30 minutes, and then boil under reflux for 45 minutes to complete the reaction. Allow to cool and filter off the sodium bromide, washing the residue with a little acetone. Remove the acetone from the filtrate on a rotary evaporator, and shake the residual organic halide with 100 ml of water. Separate the lower dark-coloured layer and wash it twice more with 50 ml portions of water incorporate sufficient crystals of sodium thiosulphate into the first portion of wash-water to decolourise the organic phase. Dry the product over anhydrous calcium sulphate, filter and distil, collecting the l-iodo-3-methylbutane at 145-147 °C. The yield is 26 g (66%). 

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