1,2,3-diheterocyclization reactions on the allenylidene ligand of a ruthenium complex

The allenylidene complex [Ru(eta(5)-C5H5) (C=C=CPh2) (CO) (PPr3i)]BF4 (1) reacts with pyrazole to afford [Ru(eta(5)-C5H5) {C=CHC(Ph)(2)N(CH)(3)N} (CO) (PPr3i)] BF4 (2) as a result of the addition of pyrazole to the allenylidene of 1. The structure of 2 was determined by an X-ray investigation, revealing a Ru-C (bicycle) distance of 2.073(4) Angstrom-. Treatment of 2 with sodium methoxide deprotonates the bicycle, which also undergoes an opening process to give the functionalized alkynyl derivative Ru(eta(5)-C5H5){C=CC (Ph)(2)N(CH)(3)N}(CO)(PPr3i) (3). The reactions of 1 with 3,5-dimethylpyrazole anti 3-methylpyrazole lead to [Ru(eta(5)-C5H5) {C=CHC(Ph)(2)NC(R)CHC(CH3)N}(CO)(PPr3i)]BF4 (R = CH3 (8), H (9)). In the presence of sodium methoxide, complex 9 affords Ru(eta(5)-C5H5){C=CC(Ph)(2)N(CH)(2)C(CH3)N}(CO)(PPr3i) (10). The allenylidene ligand of 1 also adds pyridine-2-thiol. In this case, the reaction product is [Ru(eta(5)-C5H5){C=CHC(Ph)(2)N(CH)(4)CS}(CO)(PPri(3))] BF4 (11), which yields the allenyl derivative Ru(eta(5)-C5H5){C[SC(CH)(4)N]=C=CPh2}(CO)(PPr3i) (12) by reaction with sodium methoxide.