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Shibata, T., Science of Synthesis: Stereoselective Synthesis, (2011) 3, 127.
The rhodium-catalyzed carbonylative coupling of enynes with carbon monoxide using dicarbonylchlororhodium(I) dimer {[RhCl(CO)2]2} proceeds smoothly at atmospheric pressure. Although the addition of a phosphine ligand deactivates the rhodium catalyst,[10] the cationic rhodium–diphosphine ligand complex, prepared by anion exchange using a silver salt, demonstrates high catalytic activity. This represents the first enantioselective Pauson–Khand reaction with a late-transition-metal complex using the axially chiral diphosphine ligand 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl (BINAP).[11] Unlike the chiral cyclopentadienyl ligand in the titanium complex described in Section 3.3.1.1, BINAP is commercially available and air stable, making this a practical alternative. The reaction was originally performed by heating the components at reflux in tetrahydrofuran under atmospheric pressure or a pressurized atmosphere of carbon monoxide. By this method, the yield and enantioselectivity are moderate to good depending on the substrate.[11] On the other hand, under a low partial pressure of carbon monoxide,[12] the reaction proceeds at ambient temperature with carbon- and heteroatom-tethered 1,6-enynes using 2,2′-bis[bis(3,5-dimethylphenyl)phosphino]-1,1′-binaphthyl (XylBINAP; 5) as a chiral ligand to provide the enantiomerically enriched bicyclopentenones 6 with excellent yield and enantioselectivity (Scheme 3).[13] Near-perfect enantioselectivity is achieved even with an enyne having an unsubstituted alkyne moiety.
Meeeee 8 Meeeeeeeeeeeeeee Meeeeee-Meeeeeeee Meeeee–Meeee Meeeeeee ee Meeeee eeee e Meeeee Meeeeeee Meeeeee[88]
M | M8 | Meee (e) | ee (%) | Meeee (%) | Mee |
---|---|---|---|---|---|
M | Me | 8 | 88 | 88 | [88] |
M | 8-MeMM8M8 | 8 | 88 | 88 | [88] |
M | 8-MeM8M8 | 8 | 88 | 88 | [88] |
MMe | Me | 8 | 88 | 88 | [88] |
M(MM8Me)8 | M | 8.8 | 88 | 88 | [88] |
M(MM8Me)8 | Me | 8 | 88 | 88 | [88] |
Me eee eeeee eeeeeeeee, eee eeeeeeee ee eee eeeeee eeee ee eeeeeeeee ee eeeeeeee eee eeeeeeee eeeeeee eeeeeee. Me eeeeeeee, eee eeeeeee-eeeeeeeee Meeeee–Meeee eeeeeeee ee e eeeee eeeeeee ee eeeee eee 8,8-eeeeeee eeeeeee eee eeeeeeeeeeeeeeeee 8 eeee ee eee eeeeeee ee eee eeeeee eeee (Meeeee 8).[88] Meeeeee, e eeeeeeeee eeeeee ee e eeeeeeeeee eeeee, eeee ee eeeeee eeeeeee eeeeeee (MMM), ee eeeeeeee, eee eee eeeee ee eeeee eeee eeee eeeeeeee ee eee eeeeeeee eeeeeee-eeeeeeeee eeeeeeee.
Meeeee 8 Meeeeeeeeeeeeeee Meeeeee-Meeeeeeee Meeeee–Meeee Meeeeeee ee Meeeeee Meeee[88]
M | M8 | ee (%) | Meeee (%) | Mee |
---|---|---|---|---|
M | 8-MeMM8M8 | 88 | 88 | [88] |
MMe | Me | 88 | 88 | [88] |
Meeeeeee eeeeeee-eeeeeeeee Meeeee–Meeee eeeeeeeee eee eeee ee eeee ee eeeeeee eeeeeeeeee eeeeeeeeeeeeeeee eee eeeeeee eeeeeeeeee eeeeeeeee. Meee, MMMMM eeeeeeeeeee eee eeee eeeeeeeee eeee eee eeeeee MMMMM eeeeee. Mee eeeeeee, ee eeeeee-eeeeeeee eeeeeeeeeeeeeeee 8 eee eeee eeeeeeee eeee eee eeeeeeee eeeeeeeeeee eeeeeee eeee eeeeeeeee eeeeeeeee- eee eeeeeeeeeeeeeeeeee ee eeeeeeeeeeeeeeee ee e eeeeeeeee eeeee (Meeeee 8).[88] Me e eeeeeee eeeeeee eeeeeeeee (M)-MMMMM eeeeeeeeee 8, eeeeeee eeeeeeeeee eeeeeeee eee eeeeeeeee 8,8-eeeee eee eee eeeeeeeeeee eeee eeee eeeeeeeeeeee eeeeee eeee ee M eeeee (eee eeeee ee eeeeeeee eeeee ee eeee eeeeeeeeeee) ee 88 (Meeeee 8).[88] Mee eeeeeeeeeeee eeeeeeeeee eee eee eeeeeeeee eeeee ee Meeeeee 8 eee 8 eee eeeeeeeeeee eee eeee ee ee Meeeee 8, eeeeee eee eee eeeeee eeeeeee eee eeeeeeeeee eeee.
Meeeee 8 Meeeeeeeeeeeeeee ee e Meeeeee eee e Meeeee–Meeee Meeeeeee[88]
Meeeee 8 Meeeeee Meeeeeeeee eee e Meeeee–Meeee Meeeeeee[88]
Meeeeeeeeeee Meeeeeeee
Meeeeeeeeeeeeeeee 8; Meeeeee Meeeeeeee:[88]
MMMMMMM: Meeeee eeeeeeee ee eeeeeeeee eeeeeeeee eee eeeee, eee eeeeeeee ee eeeeee eeeeeeeeeeeeee eee eeeeeee eeee ee e eeee.
[MeMe(MM)8]8 (8.8 ee, 8.888 eeee, 8 eee%), (M)-MeeMMMMM (88.8 ee, 8.888 eeee, 88 eee%), eee MMM (8 eM) eeee eeeee ee e eeeee, eee eee eeeeeee eee eeeeeee eee 88 eee ee 88 °M eeeee ee eeeeeeeeeee eeeeeeee ee eeeee. M eeee ee MeMMe (8.8 ee, 8.888 eeee, 88 eee%) ee MMM (8 eM) eee eeeee, eee eee eeeeeeeee eeeeeee eee eeeeeee eee e eeeeeee 88 eee ee 88 °M. Mee eeeee eeeeeeeeee eee eeeeeeee eeee MM ee eeeee (MM/eeeee 8:88, eeeee 8 eee), eee eeee e eeee ee ee eeeee (8.888 eeee) ee MMM (8 eM) eee eeeee. Mee eeeeeee eee eeeeeee ee 88 °M eee, eeeee eeeeeeeeee ee eee eeeeeeee, eeeeee eee eee eeeeeeee ee eee eeee, eee eee eeeee eeeeeee eee eeeeeeeeeeee eeeee eeeeeee eeeeeeee. Mee eeeee eeeeeee eee eeeeeeee ee eeeeee eeeeeeeeeeeeee (eeeeee eee, eeeeee/MeMMe) ee eeeeee eee eeee eeeeeeeeeee.
Meeeeeeeeeeeeeeee 8; Meeeeee Meeeeeeee:[88]
MMMMMMM: Meeeee eeeeeeee ee eeeeeeeee eeeeeeeee eee eeeee, eee eeeeeeee ee eeeeee eeeeeeeeeeeeee eee eeeeeee eeee ee e eeee.
[MeMe(eee)]8 (88 ee, 8.88 eeee), (M)-MMMMM (88 ee, 8.8 eeee), eee M8M/8,8-eeeeeee (8:8; 8 eM) eeee eeeee ee e eeeee, eee eee eeeeeee eee eeeeeee eee 88 eee ee ee. M eeeeeee eeeeee eeee MM(e) eee eeee eeeeeeee ee eee eeeee. Meeee eeeeeee eeeeeeee eee 88 eee, ee eeeee (8.8 eeee), eeeeee eeeeeee eeeeeee (88 ee, 8.8 eeee), eee M8M (8 eM) eeee eeeee, eee eee eeeeeeeee eeeeeee eee eeeeeee ee 88 °M eee 8.8 e. Meeee eee eeee eee eeee eeeeee ee ee, MM8Me8 (88 eM) eee eeeee. M8M eee eeeeeee ee eeeee eeeee MeMM8, eee eeee eee eeeee eeeeeeee eeee eeeeeeee ee eeeeee eeeeeeeeeeeeee (eeeeee eee, eeeeee/Me8M) ee eeeeee eee eeee eeeeeeeeeee.
References
[10] | Meee, M.; Meeeeeeee, M.; Meeeeeee, M., Meee. Meee., (8888), 888. |
[11] | Meeee, M.; Meee, M. M.; Meee, M. M., M. Me. Meee. Mee., (8888) 888, 8888. |
[12] | Meeeeeeee, M.; Meee, M.; Meeeeeee, M., M. Meeeeeeee. Meee., (8888) 888, 88. |
[13] | Mee, M. M.; Mee, M. M.; Meeeeeeeeeeeee-Meeee, M.; Meeêe, M.-M.; Meeee, M., M. Mee. Meee., (8888) 88, 8888. |
[14] | Mee, M. M.; Meee, M.; Mee, M. M.; Meeee, M. M., Meeeeeeee, (8888), 8888. |
[15] | Mee, M. M.; Meee, M.; Mee, M. M.; Meeee, M., Mee. Meeee. Meeee., (8888) 888, 88. |