Synthesis of Optically Active Tetrahedral Clusters through Ester Exchange Catalyzed by Lipase

Reactions of the monoanions [(η5-C5H4R)M2(CO)3]- with ArCH(Me)COOCH2C2H(μ3-C)Co2(CO)6 (4) in THF at 60 °C gave the functional cluster derivatives ArCH(Me)COOCH2C2H(μ3-C)CoM2(CO)5(η5-C5H4R) (1a−d:  M2 = Mo, W; R = CO2Me, C(O)Me). Similarly, reactions
of {[(η5-C5H4)C(O)OCH2(OH)CH3]M2(CO)3}- (M2 = Mo, W) with (μ3-S)M1Co2(CO)9 (M1 = Fe,
Ru) gave the tetrahedral metal clusters (μ3-S)CoM2M1(CO)8[(η5-C5H4)C(O)OCH2(OH)CH3]
(8a−d:  M1 = Fe, Ru; M2 = Mo, W). Treatment of the two metal clusters 1a−d and three
metal clusters 8a−d with methanol respectively in the presence of lipase at 50 °C for 1 h
afforded the optically active cluster derivatives HOCH2C2H(μ3-C)CoM2(CO)5(η5-C5H4R) (6a−d:  M2 = Mo, W; R = CO2Me, C(O)Me) and (μ3-S)CoM2M1(CO)8[(η5-C5H4)C(O)OCH3] (9a−d:
M1 = Fe, Ru; M2 = Mo, W). The products were separated by silica gel chromatography. The
conditions of the lipase reactions were discussed. All the compounds in the global process
were characterized by element analysis, and IR and 1H NMR spectroscopy. The structures
of clusters 8c and 9c have been determined by single-crystal X-ray diffraction.

单阴离子[(η⁵-C₅H₄R)M₂(CO)₃]⁻ 与芳基（aryl, Ar）CH(Me)COOCH₂C₂H(μ₃-C)Co₂(CO)₆（化合物4）在四氢呋喃（tetrahydrofuran, THF）中于60 ℃下反应，得到官能化团簇衍生物ArCH(Me)COOCH₂C₂H(μ₃-C)CoM₂(CO)₅(η⁵-C₅H₄R)（1a−d：M₂=Mo、W；R=甲氧羰基（methoxycarbonyl, CO₂Me）、乙酰基（acetyl, C(O)Me））。类似地，{[(η⁵-C₅H₄)C(O)OCH₂(OH)CH₃]M₂(CO)₃}⁻（M₂为Mo、W）与(μ₃-硫桥)M¹Co₂(CO)₉（M¹为Fe、Ru）反应，得到四面体金属团簇(μ₃-S)CoM₂M¹(CO)₈[(η⁵-C₅H₄)C(O)OCH₂(OH)CH₃]（8a−d：M¹=Fe、Ru；M₂=Mo、W）。将金属团簇1a−d与8a−d分别在脂肪酶存在下、于50 ℃与甲醇反应1小时，得到光学活性团簇衍生物HOCH₂C₂H(μ₃-C)CoM₂(CO)₅(η⁵-C₅H₄R)（6a−d：M₂=Mo、W；R=甲氧羰基（CO₂Me）、乙酰基（C(O)Me））与(μ₃-S)CoM₂M¹(CO)₈[(η⁵-C₅H₄)C(O)OCH₃]（9a−d：M¹=Fe、Ru；M₂=Mo、W）。产物通过硅胶柱色谱法进行分离纯化。本研究对脂肪酶催化反应的条件进行了讨论。全过程所得到的全部化合物均通过元素分析、红外光谱（infrared spectroscopy, IR）与氢核磁共振波谱（proton nuclear magnetic resonance, ¹H NMR）进行了结构表征。团簇8c与9c的分子结构已通过单晶X射线衍射法（single-crystal X-ray diffraction）得以确定。