Synthesis of Novel Organometallic Compounds Containing η1-Carbon Polycyclic Ligands: Condensation of Propargyl Alcohol with the Allenylidene Ligand of [Ru(η5-C5H5)(CCCPh2)(CO)(PPri3)]BF4

The allenylidene complex [Ru(η 5 -C 5 H 5 ){C C CPh 2 }(CO)(PPr i 3 )]BF 4 ( 1 ) reacts with propargyl alcohol to give the α,β-unsaturated alkoxycarbene derivative [Ru(η 5 -C 5 H 5 ){C(OCH 2 C⋮CH)CH CPh 2 }(CO)(PPr i 3 )]BF 4 ( 2 ). The structure of 2 was determined by an X-ray investigation, revealing a Ru−C distance of 1.965(4) Å. Treatment of 2 with 1 equiv of Na 2 CO 3 affords [Ru(η 5 -C 5 H 5 ){9-phenyl-1,3-dihydronaphtho[2,3- c ]-1-furanylidene}(CO)(PPr i 3 )]BF 4 ( 3 ), which reacts with NaBH 4 to give Ru(η 5 -C 5 H 5 ){CH 2 (1-phenyl-3-hydroxymethyl-2-naphthyl)}(CO)(PPr i 3 ) ( 4 ). The structure of 3 was determined by an X-ray diffraction analysis, revealing a Ru−C bond length of 2.004(2) Å. Treatment of 2 with 3 equiv of NaOCH 3 leads to a mixture of compounds containing the racemic form (Ru R,C R;Ru S,C S )-Ru(η 5 -C 5 H 5 ){9-phenyl-1,3-dihydronaphtho[2,3- c ]-1-furanyl}(CO)(PPr i 3 ) ( 5 ) as the main component. This racemic form was obtained as a pure solid by passing the crude products through an Al 2 O 3 column using diethyl ether as eluent. The structure of 5 was also determined by an X-ray diffraction analysis. In this case, the investigation reveals a Ru−C distance of 2.203(3) Å. When the crude products were passed through an Al 2 O 3 column using a pentane/diethyl ether (5:1) mixture, the epimerization of 5 into (Ru R,C S;Ru S,C R )-Ru(η 5 -C 5 H 5 ){9-phenyl-1,3-dihydronaphtho[2,3- c ]-1-furanyl}(CO)(PPr i 3 ) ( 6 ) was observed. When the above-mentioned chromatography is carried out using an increasing polarity mixture of toluene/diethyl ether (from 10:1 to 1:10) as eluent, the transformation of 5 into its isomer Ru(η 5 -C 5 H 5 ){CH 2 (1-phenyl-3-carboxa-2-naphthyl)}(CO)(PPr i 3 ) ( 7 ) occurs. The complex Ru(η 5 -C 5 H 5 ){9-phenyl-3,3a-dihydronaphtho[2,3- c ]-1-furanyl}(CO)(PPr i 3 ) ( 8 ) was also synthesized, by passing 2 through an Al 2 O 3 column using a tetrahydrofuran/dichloromethane (5:1) mixture as eluent.