OXYMERCURATION OF Δ⁵-[2,2,2]-BICYCLOÖCTENE

Abstract

It has now been shown that an earlier assignment of configuration in which 1,4-Tr-ethylene-A:-cyclohexenedicarbosylic acids and their derivatives were presumed to form with lnercllric salts 5-~-liydroxy-6-~-a~iioi~on~erc~~ri-l,4-~~-ethylei~ec~~clohexa~~eclic~~r~~oxylic acid clerivatives is illcorrect. Instead 5-~-hydrosy-6-~-a~~ionomcrc~~ri-l,4-~~-ethylenecsclo1iex~~~ieclicarboxylic acid derivatives are formed, similarly ~r i t h the homologous 5-L-hydroxy-6-~-ai1ionornercuri-1,4-n1ethyle11ecyclohexane-2,3-dicarbox~~lic acid deri\.atives. 'l'his similarity is exemplified by comp~rable dipole nlomcnts. T h e exception is 5 -~-1~~d r o x~-(~-~-c l~l o r o m c r c u r i -l ,~-~~-1~~e t h~l enecyclohesanc-2,3-~J-dici~rboxylic acid, ;,-lactonc, \vhich has a configuration opposite to all of the others of these series having boat-type cyclohexai~e ring col~forniations. The csception is attrib~ifecl to steric elfects.The osymercuration of As-[2,2,21-13ic)-clooctene has bee11 reportecl and the stereochenlistry has been specifiecl (I). I t has 1101~ been proved that this co~lligurational assignnlent is incorrect. The error may be su~nnlarizecl in t e r~n s of t~v o for~ilulae reproducecl here, together with their identifying numbers, from page 719 of the previous report (1). D~~r i n g the present investigation it has been found that the salile dicarbox)ilic acid, y-lactone, may be obtained by oxy~llercuration of 1,4-ethylene-aj-c~~cloI1exe1~e-2,3-J~-dicarboxylic anhydride (I) as was fornlerly obtained from dimethyl 1,4-TT-etlzyIeue-~5-c~~clohesene-2,~3-JJ-dicarbos~~late. The anh!~dride seelils to survive as such in aqueous media. However, a ~nercuric salt is formed by aclditioll of mercuric cllloride to the aqueous solution of the anhydride. Oxy~llercuration occurs very rapidly in this acidic system, and neutralization is required only to avoid an equilibriu~ll due to the reverse reaction, deor;)~mercuration. By analozy with the oxy~nercuratio~l reactions of the 1,4-TT-methylene- For personal use only.