CONDENSATIONS BY SODIUM. XXXVIII. THE METALATION OF tert-BUTYLBENZENE BY AMYLSODIUM AND THE EFFECTS OF ASSOCIATED SALTS^{1, 2}

Abstract

IKTRODUCTIONThis work was intended to be a study of the metalation of the benzene nucleus under the directing influence of an alkyl group which couId not itself be metalated, but steric factors probably limit the scope of polar influence. KO ortho metalation occurs. Only one dimetalation, the m,m', can take place because of the hindrance at the two ortho positions and the failure of sodium to attack a position adjacent to another sodium ion on the ring. Nevertheless some excellent demonstrations of the effects of associated salts, which is one of the special aspects of the work in this laboratory, have been achieved.

Halogen–sodium exchange enables efficient access to organosodium compounds

“…Despite the synthetic promise of such species, the potential of multimetalation remains underutilized, even in organolithium chemistry 3,16,17,27,28 . Double sodiation via deprotonation has been reported 3,14,16,17,[29][30][31][32][33][34][35][36][37][38][39][40][41] , but efficient triple or quadruple sodiation has not been known to date. Our halogen-sodium exchange method enabled the regioselective access to tri-and tetrasodiated compounds (Fig.…”

METALATION OF THE alpha CARBON OF ALKYLARYL HYDROCARBONS1, 2

“…In the dimetalation of benzene by amylsodium ( 9), lithium alkoxides favored the meta position and the potassium ion favored the para position. In the metalation of terf-butylbenzene, one type of alkoxide favored dimetalation while others favored monosubstitution (10).…”

Organosodium and Organopotassium Compounds Part I: Properties and Reactions

“…The interpretation of metalation as an electrophilic reaction [87] or as a free-radical process [88] a-Elimination increases when potassium is used in place of sodium but is negligibly small with lithium.…”

“…The seeming randomness with which organometallic bases bring about metal-hydrogen exchangesometimes in the orthoand sometimes in the rneta-positionhas prompted extensive discussions of the underlying mechanism. The interpretation of metalation as an electrophilic reaction [87] or as a free-radical process [88] is obsolete. It is now known that the reaction occurs by a nucleophilic, or more correctly, a protophilic [89], attack by the base.…”