- Enantio- and Diastereoselective, Complete Hydrogenation of Benzofurans by Cascade Catalysis
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We report an enantio- and diastereoselective, complete hydrogenation of multiply substituted benzofurans in a one-pot cascade catalysis. The developed protocol facilitates the controlled installation of up to six new defined stereocenters and produces architecturally complex octahydrobenzofurans, prevalent in many bioactive molecules. A unique match of a chiral homogeneous ruthenium-N-heterocyclic carbene complex and an in situ activated rhodium catalyst from a complex precursor act in sequence to enable the presented process.
- Gallagher, Timothy,Glorius, Frank,Hu, Tianjiao,Moock, Daniel,Wagener, Tobias
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p. 13677 - 13681
(2021/05/10)
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- cis-Oxypalladation Complexes Derived from (1R,5R)-2(10),3-Pinadiene and Their Utilization in Pd(II)-catalyzed Enantioselective Cyclization of 2-(trans-2-Butenyl)phenols
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(1R,5R)-2(10),3-Pinadiene, when treated with either Na2PdCl4 in MeOH or Pd(OAc)2 in AcOH and NaCl, gives di-μ-chloro-bis (4a) or (4b), respectively.These complexes represent the firstly isolated cis-oxypalladation adduct.The ligand exchange of 4b with AgOAc affords di-μ-acetato-bis (5b) which serves as the catalyst for the asymmetric cyclization of 2-(trans-2-butenyl)phenols leading to 2-vinyl-2,3-dihydrobenzofurans (13).Although the enantioselectivities induced in this asymmetric cyclization are not high (1-29percent ee), noteworthy is that the cis-complex 5b affords (R)-(-)-enantiomer of 13 while the parent di-μ-acetato-bis give the (S)-isomer.As an application of the present asymmetric cyclization, attempts to synthesize (S)-(+)-tremetone have been made.
- Hosokawa, Takahiro,Imada, Yasushi,Murahashi, Shun-Ichi
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p. 3282 - 3290
(2007/10/02)
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