~2,2-Dichlorobicyclo[4.l.O]heptanefrom Cyclohexene and Dichlorocarbene by Phase Transfer Catalysis Having f i q o t t e n ahout the simrlar experiment derrrihed by Guh,' we too developed a procedure for the addition of drrhlorocarbene to ryrlohexene t o give 2 . 2 - d i c h l o n > b i r y r ~Olheptane, .l or dichlormorcarnne
Since we believe our procedure to he significantly more convenient, we now report the experimental details. P r o c e d ~ r ePut . ~ a magnetic stirring bar in a 250-ml round-bottom boiling flask. Place asteam bathon amagnetic stirrer and clamp the flaskin position below the rings of the steam bath so that the contents of the flask can he heated by steam and magnetically stirred a t the same time.3 Add t o the flask 11 ml of chloroform (135 mmole), 4.5 ml of cyclohexene (3.6 grams; 44 mmole), and 142 mgof tetra-n-butylammonium bromide (0.44mmole). Fit the flask withareflux condenser and then pour in one portion down the condenser into the flask a mixture of 18 ml of 50% NaOH (344 mmole) and 13 ml of water. Heat and stir the resultingmixture for 15 min. At the end ofthe heating period add ice in order toeool the mixture toraom temoerature and then extract it with two 30-ml oortions of ether.' Drv the combined ethereal extracts over anhvdrous mn&ium sulfate for a fea minutes. filter by g r k t y , nnd remwe the ither by distillation on the steam hnth. Distill the rrs~dueatatmospheric pressure using a flame i.r Collect the frart ion boiling hetween 192-I97T as dichl,mmorenrane. Yield: ~
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Goh, S. H., J. CHEM. EDUC., 50,678 (1973). Goh has more recently described s dihalocarbene insertion experiment: J. CHEM. EDUC.. 52.399 (1975). Isagawa, K., ~ l m u r aY.,and , Kwon, S., J. Org. Chem. 39,3171 (1974). Joshi, G. C., Singh, N., and Pande, L. M., Tetra-
hedron Lett.. ~ 14fi1 . (1972). - ~ .'\Ye have always used magnetrc stirring; presumably the mixture can be shaken hv hand. 4 T h mixture mmt be shaken rhorouphly withether in vrder u,mnkesure that dl the pruduct goes into the upper,organic layer. On some runs we had a Little trouble with foaming. 'The product appears t o he perfectly stable upon boiling a t atmospheric pressure. ~
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Cornell College Mount Vernon, Iowa 52314
Addison Ault Bradley Wright
Volume 53, Number 8, August 1976 / 489
