Reactions of Ruthenium Cp Phosphine Complex with 4,4-Disubstituted-1,6-Enynes: Effect of Methyl Substituents in the Olefinic Fraction

We studied chemical reactions of Cp(PPh3)2RuCl with nine 1,6-enyne compounds (1−4, 8, 12, 19, 21, and 22) in which the triple bond is associated with propargylic alcohol and the olefinic group has various substituted methyl groups. For the enyne compounds 1−3 with no substituted methyl group, the reaction takes place at the propargylic alcohol first giving the allenylidene complex 6 which could undergo a skeletal rearrangement to yield the disubstituted vinylidene complex 7. By changing the propargylic alcohol to propargylic ether, the reaction gives the carbene complex 10 as the major product and the butadiene complex 9 by a cyclization reaction as the minor product. For enyne 12 with two methyl groups at the terminal carbon of the olefinic part, formation of either of the carbene complexes 15 and 16 with a substituted cyclopentenyl ring at Cα or the vinylidene complex 17 is controlled by the use of solvent. For the formation of 15 and 16, a C−C bond-forming cyclization reaction is proposed to occur at Cβ in an intermediate where the triple bond is π-coordinated. However, for the vinylidene intermediate, the reaction may proceed by the formation of the allenylidene, which undergoes a retro-ene reaction to bring about cleavage of the dimethyl substituted allyl group giving 17. For two enynes 21 and 22 where each olefinic portion is internally substituted with one methyl group, two vinylidene complexes 23 and 24 each with a five-membered ring bonded at Cβ are isolated. The reaction proceeds via formation of an allenylidene intermediate followed by a cyclization at Cγ. Stabilization of the cationic charge by the presence of methyl subsituents clearly controls the reaction pathway to give different products. These chemical reactions and their mechanisms are corroborated by structure determinations of five ruthenium complexes using single crystal X-ray diffraction analysis

Reactions of Ruthenium Cp Phosphine Complex with 4,4-Disubstituted-1,6-Enynes: Effect of Methyl Substituents in the Olefinic Fraction

We studied chemical reactions of Cp(PPh3)2RuCl with nine 1,6-enyne compounds (1−4, 8, 12, 19, 21, and 22) in which the triple bond is associated with propargylic alcohol and the olefinic group has various substituted methyl groups. For the enyne compounds 1−3 with no substituted methyl group, the reaction takes place at the propargylic alcohol first giving the allenylidene complex 6 which could undergo a skeletal rearrangement to yield the disubstituted vinylidene complex 7. By changing the propargylic alcohol to propargylic ether, the reaction gives the carbene complex 10 as the major product and the butadiene complex 9 by a cyclization reaction as the minor product. For enyne 12 with two methyl groups at the terminal carbon of the olefinic part, formation of either of the carbene complexes 15 and 16 with a substituted cyclopentenyl ring at Cα or the vinylidene complex 17 is controlled by the use of solvent. For the formation of 15 and 16, a C−C bond-forming cyclization reaction is proposed to occur at Cβ in an intermediate where the triple bond is π-coordinated. However, for the vinylidene intermediate, the reaction may proceed by the formation of the allenylidene, which undergoes a retro-ene reaction to bring about cleavage of the dimethyl substituted allyl group giving 17. For two enynes 21 and 22 where each olefinic portion is internally substituted with one methyl group, two vinylidene complexes 23 and 24 each with a five-membered ring bonded at Cβ are isolated. The reaction proceeds via formation of an allenylidene intermediate followed by a cyclization at Cγ. Stabilization of the cationic charge by the presence of methyl subsituents clearly controls the reaction pathway to give different products. These chemical reactions and their mechanisms are corroborated by structure determinations of five ruthenium complexes using single crystal X-ray diffraction analysis

Reactions of Ruthenium Cp Phosphine Complex with 4,4-Disubstituted-1,6-Enynes: Effect of Methyl Substituents in the Olefinic Fraction

We studied chemical reactions of Cp(PPh3)2RuCl with nine 1,6-enyne compounds (1−4, 8, 12, 19, 21, and 22) in which the triple bond is associated with propargylic alcohol and the olefinic group has various substituted methyl groups. For the enyne compounds 1−3 with no substituted methyl group, the reaction takes place at the propargylic alcohol first giving the allenylidene complex 6 which could undergo a skeletal rearrangement to yield the disubstituted vinylidene complex 7. By changing the propargylic alcohol to propargylic ether, the reaction gives the carbene complex 10 as the major product and the butadiene complex 9 by a cyclization reaction as the minor product. For enyne 12 with two methyl groups at the terminal carbon of the olefinic part, formation of either of the carbene complexes 15 and 16 with a substituted cyclopentenyl ring at Cα or the vinylidene complex 17 is controlled by the use of solvent. For the formation of 15 and 16, a C−C bond-forming cyclization reaction is proposed to occur at Cβ in an intermediate where the triple bond is π-coordinated. However, for the vinylidene intermediate, the reaction may proceed by the formation of the allenylidene, which undergoes a retro-ene reaction to bring about cleavage of the dimethyl substituted allyl group giving 17. For two enynes 21 and 22 where each olefinic portion is internally substituted with one methyl group, two vinylidene complexes 23 and 24 each with a five-membered ring bonded at Cβ are isolated. The reaction proceeds via formation of an allenylidene intermediate followed by a cyclization at Cγ. Stabilization of the cationic charge by the presence of methyl subsituents clearly controls the reaction pathway to give different products. These chemical reactions and their mechanisms are corroborated by structure determinations of five ruthenium complexes using single crystal X-ray diffraction analysis

Reactions of Ruthenium Cp Phosphine Complex with 4,4-Disubstituted-1,6-Enynes: Effect of Methyl Substituents in the Olefinic Fraction

We studied chemical reactions of Cp(PPh3)2RuCl with nine 1,6-enyne compounds (1−4, 8, 12, 19, 21, and 22) in which the triple bond is associated with propargylic alcohol and the olefinic group has various substituted methyl groups. For the enyne compounds 1−3 with no substituted methyl group, the reaction takes place at the propargylic alcohol first giving the allenylidene complex 6 which could undergo a skeletal rearrangement to yield the disubstituted vinylidene complex 7. By changing the propargylic alcohol to propargylic ether, the reaction gives the carbene complex 10 as the major product and the butadiene complex 9 by a cyclization reaction as the minor product. For enyne 12 with two methyl groups at the terminal carbon of the olefinic part, formation of either of the carbene complexes 15 and 16 with a substituted cyclopentenyl ring at Cα or the vinylidene complex 17 is controlled by the use of solvent. For the formation of 15 and 16, a C−C bond-forming cyclization reaction is proposed to occur at Cβ in an intermediate where the triple bond is π-coordinated. However, for the vinylidene intermediate, the reaction may proceed by the formation of the allenylidene, which undergoes a retro-ene reaction to bring about cleavage of the dimethyl substituted allyl group giving 17. For two enynes 21 and 22 where each olefinic portion is internally substituted with one methyl group, two vinylidene complexes 23 and 24 each with a five-membered ring bonded at Cβ are isolated. The reaction proceeds via formation of an allenylidene intermediate followed by a cyclization at Cγ. Stabilization of the cationic charge by the presence of methyl subsituents clearly controls the reaction pathway to give different products. These chemical reactions and their mechanisms are corroborated by structure determinations of five ruthenium complexes using single crystal X-ray diffraction analysis

Ruthenium Allenylidene and Allylcarbene Complexes from 1,6-Diyne

Reactions of the four 1,6-diynes 1−3 and 7, each with one terminal propargylic alcohol and one internal triple bond containing Me3Si groups, with [Ru]−Cl ([Ru] = Cp(PPh3)2Ru) led to two types of products. In the first type, only the propargylic group is involved in the reaction leading to vinylidene, allenylidene, or acetylide complexes. A C−C bond formation of two triple bonds in 1,6-diynes gave allylcarbene products of the second type. The reaction of 1 with [Ru]−Cl yielded only the first type, giving a mixture of two cationic complexes; the allenylidene complex 8 and the phosphonium acetylide complex 9, the latter resulting from further addition of a phosphine molecule to Cγ of 8. The same reaction in the presence of excess phosphine gave 9 only. However, with an additional methyl group, the 1,6-diyne 2 reacted with [Ru]−Cl to give the allylcarbene complex 11 also with a phosphonium group on the ligand. The reaction proceeds by a cyclization reaction involving two triple bonds on the metal accompanied by a migration of a phosphine ligand to Cα. In both reactions strong affinity between alkyne and phosphine was observed, resulting in formations of P−C bonds with different regioselectivity. Addition of HCl to 11 transforms the five-electron-donor allylcarbene ligand to the four-electron-donor diene ligand along with formation of a Ru−Cl bond, giving complex 12 in high yield. From the reaction of [Ru]−Cl with diyne 3 containing a tert-butyl group at the propargylic carbon, both the allenylidene complex 13 and the allylcarbene complex 14 were obtained. The reaction of diyne 7 with [Ru]−Cl also gave both types of complexes, namely the vinylidene complex 16 and the allylcarbene complex 17. Crystal structures of complexes 9, 11, 12, and 16 have been determined by single-crystal X-ray diffraction analysis

Reactions of Ruthenium Cp Phosphine Complex with 4,4-Disubstituted-1,6-Enynes: Effect of Methyl Substituents in the Olefinic Fraction

We studied chemical reactions of Cp(PPh3)2RuCl with nine 1,6-enyne compounds (1−4, 8, 12, 19, 21, and 22) in which the triple bond is associated with propargylic alcohol and the olefinic group has various substituted methyl groups. For the enyne compounds 1−3 with no substituted methyl group, the reaction takes place at the propargylic alcohol first giving the allenylidene complex 6 which could undergo a skeletal rearrangement to yield the disubstituted vinylidene complex 7. By changing the propargylic alcohol to propargylic ether, the reaction gives the carbene complex 10 as the major product and the butadiene complex 9 by a cyclization reaction as the minor product. For enyne 12 with two methyl groups at the terminal carbon of the olefinic part, formation of either of the carbene complexes 15 and 16 with a substituted cyclopentenyl ring at Cα or the vinylidene complex 17 is controlled by the use of solvent. For the formation of 15 and 16, a C−C bond-forming cyclization reaction is proposed to occur at Cβ in an intermediate where the triple bond is π-coordinated. However, for the vinylidene intermediate, the reaction may proceed by the formation of the allenylidene, which undergoes a retro-ene reaction to bring about cleavage of the dimethyl substituted allyl group giving 17. For two enynes 21 and 22 where each olefinic portion is internally substituted with one methyl group, two vinylidene complexes 23 and 24 each with a five-membered ring bonded at Cβ are isolated. The reaction proceeds via formation of an allenylidene intermediate followed by a cyclization at Cγ. Stabilization of the cationic charge by the presence of methyl subsituents clearly controls the reaction pathway to give different products. These chemical reactions and their mechanisms are corroborated by structure determinations of five ruthenium complexes using single crystal X-ray diffraction analysis

Reactions of Ruthenium Cp Phosphine Complex with 4,4-Disubstituted-1,6-Enynes: Effect of Methyl Substituents in the Olefinic Fraction

We studied chemical reactions of Cp(PPh3)2RuCl with nine 1,6-enyne compounds (1−4, 8, 12, 19, 21, and 22) in which the triple bond is associated with propargylic alcohol and the olefinic group has various substituted methyl groups. For the enyne compounds 1−3 with no substituted methyl group, the reaction takes place at the propargylic alcohol first giving the allenylidene complex 6 which could undergo a skeletal rearrangement to yield the disubstituted vinylidene complex 7. By changing the propargylic alcohol to propargylic ether, the reaction gives the carbene complex 10 as the major product and the butadiene complex 9 by a cyclization reaction as the minor product. For enyne 12 with two methyl groups at the terminal carbon of the olefinic part, formation of either of the carbene complexes 15 and 16 with a substituted cyclopentenyl ring at Cα or the vinylidene complex 17 is controlled by the use of solvent. For the formation of 15 and 16, a C−C bond-forming cyclization reaction is proposed to occur at Cβ in an intermediate where the triple bond is π-coordinated. However, for the vinylidene intermediate, the reaction may proceed by the formation of the allenylidene, which undergoes a retro-ene reaction to bring about cleavage of the dimethyl substituted allyl group giving 17. For two enynes 21 and 22 where each olefinic portion is internally substituted with one methyl group, two vinylidene complexes 23 and 24 each with a five-membered ring bonded at Cβ are isolated. The reaction proceeds via formation of an allenylidene intermediate followed by a cyclization at Cγ. Stabilization of the cationic charge by the presence of methyl subsituents clearly controls the reaction pathway to give different products. These chemical reactions and their mechanisms are corroborated by structure determinations of five ruthenium complexes using single crystal X-ray diffraction analysis

Ruthenium Allenylidene and Allylcarbene Complexes from 1,6-Diyne

Reactions of the four 1,6-diynes 1−3 and 7, each with one terminal propargylic alcohol and one internal triple bond containing Me3Si groups, with [Ru]−Cl ([Ru] = Cp(PPh3)2Ru) led to two types of products. In the first type, only the propargylic group is involved in the reaction leading to vinylidene, allenylidene, or acetylide complexes. A C−C bond formation of two triple bonds in 1,6-diynes gave allylcarbene products of the second type. The reaction of 1 with [Ru]−Cl yielded only the first type, giving a mixture of two cationic complexes; the allenylidene complex 8 and the phosphonium acetylide complex 9, the latter resulting from further addition of a phosphine molecule to Cγ of 8. The same reaction in the presence of excess phosphine gave 9 only. However, with an additional methyl group, the 1,6-diyne 2 reacted with [Ru]−Cl to give the allylcarbene complex 11 also with a phosphonium group on the ligand. The reaction proceeds by a cyclization reaction involving two triple bonds on the metal accompanied by a migration of a phosphine ligand to Cα. In both reactions strong affinity between alkyne and phosphine was observed, resulting in formations of P−C bonds with different regioselectivity. Addition of HCl to 11 transforms the five-electron-donor allylcarbene ligand to the four-electron-donor diene ligand along with formation of a Ru−Cl bond, giving complex 12 in high yield. From the reaction of [Ru]−Cl with diyne 3 containing a tert-butyl group at the propargylic carbon, both the allenylidene complex 13 and the allylcarbene complex 14 were obtained. The reaction of diyne 7 with [Ru]−Cl also gave both types of complexes, namely the vinylidene complex 16 and the allylcarbene complex 17. Crystal structures of complexes 9, 11, 12, and 16 have been determined by single-crystal X-ray diffraction analysis

Ruthenium Allenylidene and Allylcarbene Complexes from 1,6-Diyne

Reactions of the four 1,6-diynes 1−3 and 7, each with one terminal propargylic alcohol and one internal triple bond containing Me3Si groups, with [Ru]−Cl ([Ru] = Cp(PPh3)2Ru) led to two types of products. In the first type, only the propargylic group is involved in the reaction leading to vinylidene, allenylidene, or acetylide complexes. A C−C bond formation of two triple bonds in 1,6-diynes gave allylcarbene products of the second type. The reaction of 1 with [Ru]−Cl yielded only the first type, giving a mixture of two cationic complexes; the allenylidene complex 8 and the phosphonium acetylide complex 9, the latter resulting from further addition of a phosphine molecule to Cγ of 8. The same reaction in the presence of excess phosphine gave 9 only. However, with an additional methyl group, the 1,6-diyne 2 reacted with [Ru]−Cl to give the allylcarbene complex 11 also with a phosphonium group on the ligand. The reaction proceeds by a cyclization reaction involving two triple bonds on the metal accompanied by a migration of a phosphine ligand to Cα. In both reactions strong affinity between alkyne and phosphine was observed, resulting in formations of P−C bonds with different regioselectivity. Addition of HCl to 11 transforms the five-electron-donor allylcarbene ligand to the four-electron-donor diene ligand along with formation of a Ru−Cl bond, giving complex 12 in high yield. From the reaction of [Ru]−Cl with diyne 3 containing a tert-butyl group at the propargylic carbon, both the allenylidene complex 13 and the allylcarbene complex 14 were obtained. The reaction of diyne 7 with [Ru]−Cl also gave both types of complexes, namely the vinylidene complex 16 and the allylcarbene complex 17. Crystal structures of complexes 9, 11, 12, and 16 have been determined by single-crystal X-ray diffraction analysis

Ruthenium Allenylidene and Allylcarbene Complexes from 1,6-Diyne

Reactions of the four 1,6-diynes 1−3 and 7, each with one terminal propargylic alcohol and one internal triple bond containing Me3Si groups, with [Ru]−Cl ([Ru] = Cp(PPh3)2Ru) led to two types of products. In the first type, only the propargylic group is involved in the reaction leading to vinylidene, allenylidene, or acetylide complexes. A C−C bond formation of two triple bonds in 1,6-diynes gave allylcarbene products of the second type. The reaction of 1 with [Ru]−Cl yielded only the first type, giving a mixture of two cationic complexes; the allenylidene complex 8 and the phosphonium acetylide complex 9, the latter resulting from further addition of a phosphine molecule to Cγ of 8. The same reaction in the presence of excess phosphine gave 9 only. However, with an additional methyl group, the 1,6-diyne 2 reacted with [Ru]−Cl to give the allylcarbene complex 11 also with a phosphonium group on the ligand. The reaction proceeds by a cyclization reaction involving two triple bonds on the metal accompanied by a migration of a phosphine ligand to Cα. In both reactions strong affinity between alkyne and phosphine was observed, resulting in formations of P−C bonds with different regioselectivity. Addition of HCl to 11 transforms the five-electron-donor allylcarbene ligand to the four-electron-donor diene ligand along with formation of a Ru−Cl bond, giving complex 12 in high yield. From the reaction of [Ru]−Cl with diyne 3 containing a tert-butyl group at the propargylic carbon, both the allenylidene complex 13 and the allylcarbene complex 14 were obtained. The reaction of diyne 7 with [Ru]−Cl also gave both types of complexes, namely the vinylidene complex 16 and the allylcarbene complex 17. Crystal structures of complexes 9, 11, 12, and 16 have been determined by single-crystal X-ray diffraction analysis