Bromobenzene phenyllithium from

Phenyllithium from bromobenzene and Li-wire in ether added at 0-5° during 25 min. to a vigorously stirred suspension of finely powdered isatin in ether, and stirring continued 2 hrs. at 20° 3-phenyldioxindole (startg. m. f. 303). Y 75%. J. M. Bruce, Soc. 1959, 2366. 

Cognate preparation. 3,3,5-Trimetkyl-l-methylenecyclohexane. Prepare an ethereal solution of phenyllithium by the procedure described in Expt 8.32, using 2.7 g (0.39 mol) of lithium shavings, 26 g (17.5 ml, 0.16 mol) of dry redistilled bromobenzene and 85 ml of anhydrous ether. After the conversion to phenyllithium is complete dilute the solution with a 15 ml portion of anhydrous ether and decant the solution from any unreacted lithium [Expt 8.32 Note (2)] into a clean three-necked 250-ml flask equipped with a nitro-... 

In some cases metal-halogen exchange competes with the Wurtz-Fittig reaction.320,321 Wittig and Witt, for example, obtained bromobenzene and bibenzyl instead of diphenylmethane from phenyllithium and benzyl bromide (for details see the original paper322). 

Piperidine or lithium piperidide and benzyne form N-phenylpiperidine, as expected, but the same product (40-50%) was also obtained unexpectedly from V-methylpiperidine, fluorobenzene, and phenyllithium before the formation of benzyne under these conditions was properly recognized. A series of N-alkylmorpholines gives secondary and tertiary aniline derivatives 213 and 214 when treated with bromobenzene and sodium amide. A route for formation of these products via the ylid 211 is outlined in Scheme 19, in which the formation of 211 is similar to that of 16 in Scheme 2 and the step 212 -+ 213 is similar to the decomposition of 33 in Scheme 5. The final... 

Tho organolithium reagent was generated in situ in etfier from bromobenzene. Commercial phenyllithium (Foote Mineral Company, ca. 20% in ether-benzene) and six equivalents of lithium were used. 

An ethereal soln. of Fe-pentacarbonyl added slowly at -40° to a stirred soln. of phenyllithium prepared from bromobenzene and lithium, stirring continued 3 hrs., benzyl bromide in ether added, kept 2 hrs. at -40°, benzene added, and stirred with slow warming to 50° benzyl phenyl ketone. Y 57%. F. e. s. Y. Sawa, M. Ryang, and S. Tsutsumi, Tetrah. Let. 1969, 5189. 

An ethereal soln. of p-chlorobenzaldehyde dimethylhydrazone added dropwise at —10 to 36 to a soln. of phenyllithium prepared from bromobenzene and Li in ether, stirring continued for several hrs. N- (phenyl-p-chlorophenylmethyl) -N jN -dimethyldrazine. Y 86%. F. e., also sec. amines from azomethines (cf. Synth. Meth. 4, 643), and alkoxylamines from alkoximes, s. A. Marxer and M. Horvath, Helv. 47, 1101 (1964). 

Ring cleavage. Tetraphenyl-l,3-cy-clobutanedione added portionwise to an ethereal soln. of phenyllithium prepared from bromobenzene and Li, refluxed 1.5 hrs. after the reaction has subsided, and allowed to stand overnight si/m-tetraphenyl-acetone (Y 96%) and triphenyl-carbinol (Y 95%).— The startg. m. failed to give a noticeable reaction with phenylmagnesium bromide even when heated at 66° for 6 hrs. 

Resorcinol dimethyl ether in ether added under dry Ng to a soln. of phenyllithium prepared from Li and bromobenzene in ether, stirred 60 hrs. at room temp., methyl iodide added with ice-cooling, and refluxed 3 hrs. -> 2,6-dimethoxy-toluene. Y 95%. A. K. Tanaka, A. Kobayashi, and K. Yamashita, Agri. Biol. Chem. (Tokyo) 37, 669 (1973). 

Benzocyclobutenone added to phenyllithium, prepared in situ from bromobenzene and excess Li, in ether at ca. -78, then NHg distilled in, and quenched with Na-benzoate NH4CI ... 

Phenylacetylene added to a soln. of phenyllithium prepared from 0.8g.-atom of Li and 0.3 mole of bromobenzene, stirred 30 min., (ferrocenyImethyl)-tri-methylammonium iodide added, the ether distilled off under Ng and replaced with tetrahydrofuran, then refluxed 48 hrs. with stirring 3-ferrocenyl-l-phenylprop-l-yne. Y 43%.—Excess phenyllithium must be avoided. P. L. Pauson and W. E. Watts, Soc. 1963, 2990. 

Scheme 1-1. Piperidine shuttling lithium from phenyllithium to bromobenzene, thus generating the labile 2-bromophenyllithium and, next, "benzyne" (1,2-dedihydrobenzene) that is instantaneously trapped by lithium piperidide.

---