Nucleophiles Derived from Group 16 O, S, Se, and Te

The anions derived from phenols are bidentate nucleophiles and can react through of the O- or the C-atoms. For example, the 2-naphthoxide ions 65 react with ArX to give substitution only at C-1 of the naphthalene ring [61]. In this reaction, the intermediated Ar radical couples in C-1 of 65 to yield the radical anion 66, which by ET gives the product 67 that after tautomerization yields the more stable products 68 (Eq. 10.25). The rates of reactions of 2- and 4-anisyl and 2-methoxy-l-naphthyl radicals with 65 were determined (10 -10 M s ) using an indirect method, a competition of the coupling reaction with the H-atom abstraction from the DMSO [62]  

Other examples of this approach are the photostimulated reaction of 1-iodonaphthalene with ions 65 that afford the substitution product 1,1 -binaphthyl-2-ol (53%) [61] and the photostimulated reaction of Phi with the anion of 9-phenanthrol that afforded lO-phenylphenanthren-9-ol in 53% 

The photostimulated reaction of 4-hydroxycoumarin 69 with Arl (Ar=Ph, 4-anisyl, 2-anisyl, and 1-naphthyl) and f-BuOK as base in DMSO has been investigated, and 3-aryl-4-hydroxycoumarins 70 were obtained in good yields (Eq. 10.26) [63]  

Ar with low-energy LUMO SCHEME 10.12 S l reactions with sulfur-centered anions. 

When 2-pyrimidinethiolate ions are allowed to react with o-, m-, and the monosub- 

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