Ruthenium-Catalyzed Asymmetric Hydrohydroxyalkylation of Butadiene: The Role of the Formyl Hydrogen Bond in Stereochemical Control

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• 作者：Matthew N. Grayson ; Michael J. Krische ; K. N. Houk
• 刊名：Journal of the American Chemical Society
• 出版年：2015
• 出版时间：July 15, 2015
• 年：2015
• 卷：137
• 期：27
• 页码：8838-8850
• 全文大小：994K
• ISSN：1520-5126

文摘

The catalyst generated in situ from RuH₂(CO)(PPh₃)₃, (S)-SEGPHOS, and a chiral phosphoric acid promotes asymmetric hydrohydroxyalkylation of butadiene and affords enantioenriched 伪-methyl homoallylic alcohols. The observed diastereo- and enantioselectivities are determined by both the chiral phosphine and chiral phosphate ligands. Density functional theory calculations (M06/SDD-6-311G(d,p)鈥揑EFPCM(acetone)//B3LYP/SDD-6-31G(d)) predict that the product distribution is controlled by the kinetics of carbon鈥揷arbon bond formation, and this process occurs via a closed-chair Zimmerman鈥揟raxler-type transition structure (TS). Chiral-phosphate-dependent stereoselectivity arising from this TS is enabled through a hydrogen bond between the phosphoryl oxygen and the aldehyde formyl proton present in TADDOL-derived catalysts. This interaction is absent in the corresponding BINOL-derived systems, and the opposite diastereo- and enantioselectivity is observed. Additional factors influencing the stereochemical control are determined.