共 105 条
Aminocyclopentadienyl ruthenium complexes as racemization catalysts for dynamic kinetic resolution of secondary alcohols at ambient temperature
被引:153
作者:
Choi, JH
[1
]
Choi, YK
[1
]
Kim, YH
[1
]
Park, ES
[1
]
Kim, EJ
[1
]
Kim, MJ
[1
]
Park, JW
[1
]
机构:
[1] Pohang Univ Sci & Technol, Div Mol & Life Sci, Dept Chem, Natl Res Lab Chirotechnol, Pohang 790784, Kyungbuk, South Korea
关键词:
D O I:
10.1021/jo0355799
中图分类号:
O62 [有机化学];
学科分类号:
070303 ;
081704 ;
摘要:
Aminocyclopentadienyl. ruthenium complexes, which can be used as room-temperature racemization catalysts with lipases in the dynamic kinetic resolution (DKR) of secondary alcohols, were synthesized from cyclopenta-2,4-dienimines, Ru-3(CO)(12), and CHCl3: [2,3,4,5-Ph-4(eta(5)-C4CNHR)]Ru-(CO)(2)Cl (4: R = i-Pr; 5: R = n-Pr; 6: R = t-Bu), [2,5-Me-2-3,4-Ph-2(eta(5)-C4CNHR)]Ru(CO)(2)Cl (7: R = i-Pr; 8: R = Ph), and [2,3,4,5-Ph-4(eta(5)-C4CNHAr)]Ru(CO)(2)Cl (9: Ar = p-NO2C6H4; 10: Ar = p-ClC6H4; 11: Ar = Ph; 12: Ar = p-OMeC6H4; 13: Ar = p-NMe2C6H4). The tests in the racemization of (S)-4-phenyl-2-butanol showed that 7 is the most active catalyst, although the difference decreased in the DKR. Complex 4 was used in the DKR of various alcohols; at room temperature, not only simple alcohols but also functionalized ones such as allylic alcohols, alkynyl alcohols, diols, hydroxyl esters, and chlorohydrins were successfully transformed to chiral acetates. In mechanistic studies for the catalytic racemization, ruthenium hydride 14 appeared to be a key species. It was the major organometallic species in the racemization of (S)-1-phenylethanol with 4 and potassium tertbutoxide. In a separate experiment, (S)-1-phenylethanol was racemized catalytically by 14 in the presence of acetophenone.
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页码:1972 / 1977
页数:6
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