CHEMISTRY AND KINETICS OF ALPHA-NAPHTHYL(PHOSPHONYL)CARBENE AND BETA-NAPHTHYL(PHOSPHONYL)CARBENE - EFFECTS OF POSITIONS ON NEIGHBORING PHOSPHONATE PARTICIPATION

A series of naphthyldiazomethanes 1 having either (dimethyl)phosphonyl [a: (MeO)(2)P(O)-] or sodium (monomethyl)phosphonate [b: (MeO)(NaO)P( O)-] groups at positions alpha or beta have been prepared and the effe cts of-these substituents on the naphthylcarbenes (2) generated by pho tolysis of the corresponding diazo compounds have been investigated bo th by product analysis and by spectroscopic means. A marked difference lin the reaction patterns and reactivities between the alpha- and bet a-isomers of 2a can be explained in terms of differences in electrophi licity of the carbenic centre due to the naphthyl moiety HOMO and of t he interaction between the carbene centre and the peri-hydrogen. On th e other hand, the dramatic increase in the reactivity towards the OH b ond relative to the alkenic double bond of the phosphonate anion indic ates that the neighbouring phosphonate group must interact with the va cant p-orbital of a singlet carbene and thus reduce the electrophilici ty of the carbene.