Formation of (Diphenylphosphino)naphthalenes by Double Insertion of (Alkynyl)diphenylphosphines into Nickel(0)−Benzyne Complexes

(Alkynyl)diphenylphosphines Ph 2 PC⋮CR (R = H, Me, Ph, PPh 2 ) undergo double insertion into the nickel(0)−benzyne bond of the complexes [Ni{(1,2-η)-4,5-X 2 C 6 H 2 }(PEt 3 ) 2 ] (X = H ( 1a ), F ( 1b )) to give mixtures of nickel(0) complexes containing (diphenylphosphino)naphthalenes, which in some cases are formed with high regioselectivity. Bromination of the mixtures of nickel(0) complexes obtained from Ph 2 PC⋮CR (R = Me, Ph) and 1a or 1b gives in high yield the chelate NiBr 2 complexes [NiBr 2 {6,7-X 2 C 10 H 2 -1,4-Y 2 -2,3-(PPh 2 ) 2 }] (X = H, Y = Me ( 6a ), Ph ( 11a ); X = F, Y = Me ( 6b ), Ph ( 11b )), from which the corresponding 1,4-disubstituted 2,3-naphthylenebis(diphenylphosphines) 12a, 13a, 12b, and 13b can be liberated by treatment with NaCN in DMSO at 60 °C or dimethylglyoxime/ammonia at room temperature. Derivatives in which only one of the phosphorus atoms is oxidized, 6,7-X 2 C 10 H 2 -1,4-Me 2 -2-PPh 2 -3-P(O)PPh 2 (X = H ( 15a ), F ( 15b )), have also been prepared. The regioselectivity of the reactions of Ph 2 PC⋮CH with 1b is poorer than that of Ph 2 PC⋮CR (R = Me, Ph), and products with a 1,3-substitution pattern predominate. Reaction of Ph 2 PC⋮CPPh 2 (dppa) with 1a gives, after addition of bromine, a pair of isomers in which NiBr 2 is attached to the phosphorus atoms at the 2,3- and 1,2-positions, respectively, of the tetrakis(tertiary phosphine) species C 10 H 4 -1,2,3,4-(PPh 2 ) 4 ( 19 ). The molecular structures of complexes 11b and [NiBr 2 {C 10 H 4 -1,2,3-(PPh 2 ) 3 -4-{P(O)Ph 2 }-κ P 1, P 2 }] ( 18 ), and of a disordered 73:27 mixture of the bis(diphenylphosphine oxides) C 10 H 4 -1,4-(PPh 2 ) 2 -2,3-{P(O)Ph 2 } 2 ( 20 ) and C 10 H 4 -1,2-(PPh 2 ) 2 -3,4-{P(O)Ph 2 } 2 ( 21 ) obtained by partial oxidation of 19, have been determined by single-crystal X-ray diffraction. The regioselectivities of the insertions of Ph 2 PC⋮CMe and Ph 2 PC⋮CH into 1a and 1b are similar to those of MeC⋮CCO 2 Me and HC⋮CCO 2 Me, respectively, and factors that influence them are discussed.