The synthesis of oxygenated naphthyl stannanes possessing ortho-methoxy substituents for use in Stille coupling reactions

The preparation of oxygenated naphthyl stannanes bearing an ortho-methoxy s ubstituent is described, including stannanes (23) and (25) which are key in termediates for the synthesis of dimeric pyranonaphthoquinone antibiotics. Stannanes (17), (19) and (21)-(23) were obtained by metal-halogen exchange of the corresponding bromonaphthalenes. In an alternative approach to effec t stannylation, a palladium(0)-mediated coupling reaction using hexaalkyldi tin reagents was examined. The Stille coupling reaction between naphthyl st annanes (23) and (25) and the corresponding bromonaphthalenes (11) and (24) failed to effect coupling to the desired binaphthyls.