INTRAMOLECULAR ALKOXYMERCURATION OF OLEFINS AND STABILIZATION OF THE RESULTING ORGANOMERCURIALS

Quenching of oxymercuration with CuCl has been found superior to the classical method using aqueous NaCl or KBr. Oxymercuration products with an antiperiplanar arrangement of the C-HgX and C-O bonds (e.g. diaxial as in 2) are particularly prone to reversion to the olefin (1) when treated with hard reagents, such as NaCl, KBr, CuCl2, CoCl2, HCl, etc. The reversal is apparently boosted by the stereoelectronic effect and electrophilic catalysis. By contrast, quenching of the primarily formed organomercurial 2 with soft reagents, namely with CuCl, PdCl2 K2PtCl4, etc. reliably affords the desired chloromercury compound 3.