Photostimulated Reactions of o-Dihalobenzenes with Nucleophiles Derived from the 2-Naphthyl System. Competition between Electron transfer, Fragmentation, and Ring Closure Reactions

BAUMGARTNER, M.T; PIERINI, A. B.; ROSSI, R.A.

JOURNAL OF ORGANIC CHEMISTRY

AMER CHEMICAL SOC

Lugar: Washington; Año: 1993 vol. 58 p. 2593 - 2598

0022-3263

The photostimulated reaction of o-dihalobenzenes 2 with 2-naphthoxide ions 1-0 gave the substitution product on carbon 1 of the naphthyl moiety with retention of halogen (I, Br, and C1) 3 as well as the ring closure product benzo[blnaphtho[1,2-dlfuran (4), with product 3 being an intermediate in the formation of 4. The products obtained in the photostimulated reaction of 2-naphthalenethiolate ions 1-S with 2 depend on the halogens. When both nucleofugal groups are iodine, only the ring closure product benzo[bInaphtho[l,2-d1 thiophene (10) is obtained. With o-bromoiodobenzene, the photostimulated reaction gave 10 and the substitution product on sulfur with retention of bromine, while with o-chloroiodobenzene the only observed product was the substitution product on sulfur with retention of chlorine. The photostimulated reaction of 2 with 2-naphthaleneselenolate ions 1-Se gave the same amount of cyclized product benzo[blnaphtho[l,2-dlselenophene (14) and the substitution product on selenium without retention of halogen 15, although in an overall low yield. It is suggested that all these reactions occur by the SRN~ mechanism. Theoretical studies support the different behavior found with the nucleophiles derived from the 2-naphthyl system.