Monday, February 24, 2014
Léa Benkoski and Tristan H. Lambert
Construction of Multiple Stereocenters
Erick M. Carreira at ETH Zürich reported (Science 2013, 340, 1065. ) the enantioselective α-allylation of aldehyde 1 with alcohol 2 to produce 3 using a dual catalytic system involving a chiral iridium complex and amine 5. This stereodivergent method allows access to all of the possible stereoisomers of 3. In a conceptually related process, John F. Hartwig at the University of California at Berkeley reported (J. Am. Chem. Soc. 2013, 135, 2068. ) the highly stereoselective allylic alkylation of azlactone 6 with allylic carbonate 7 catalyzed by a combination of Ir(cod)Cl2, ligand 9, and racemic silver phosphate 10.
An enantioselective three-component Mannich-type reaction of tert-butyl diazoacetate, aniline, and imine 11 to produce α,β-bis(arylamino) acid derivative 13 under dual catalysis with Rh2(OAc)4 and acid 12 was developed (Synthesis 2013, 45, 452. ) by Wenhao Hu at the Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development. Keiji Maruoka at Kyoto University reported (Chem. Commun. 2013, 49, 1118. ) a one-pot cross double-Mannich reaction of acetylaldehyde (14) and imines 16 and 17 using axially chiral amino sulfonamide 15 to obtain densely functionalized 1,3-diamine 18 as a single stereoisomer.
Jeffrey S. Johnson at the University of North Carolina at Chapel Hill reported (Org. Lett. 2013, 15, 2446. ) the asymmetric synthesis of enantioenriched anti-α-hydroxy-β-amino acid derivative 21 from 19 by treatment with oxone followed by catalytic hydrogenation using Ru(II) complex 20. Naoya Kumagai and Masakatsu Shibasaki at the Institute of Microbial Chemistry found (Org. Lett. 2013, 15, 2632. ) that a silver complex of bisphosphine 24 effected a syn-selective and highly enantioselective Mannich-type reaction of aldimine 22 and α-sulfanyl lactone 23 to furnish the stereodiad 25 with very high ee.
The enantioselective homocrotylation of octanal (26) with cyclopropylcarbinylboronate 27 to produce alcohol 28 with high ee was disclosed (J. Am. Chem. Soc. 2013, 135, 82. ) by Isaac J. Krauss at Brandeis University and Kendall N. Houk at University of California. Benjamin List at the Max-Planck-Institut für Kohlenforschung reported (J. Am. Chem. Soc. 2013, 135, 6677. ) the enantioselective epoxidation of cyclohexenone 29 utilizing cinchona alkaloid-derived organocatalyst 30.
Hao Xu at Georgia State University reported (J. Am. Chem. Soc. 2013, 135, 3343. ) a diastereoselective intramolecular aminohydroxylation of olefin 32 to produce 33 via catalysis by an iron (II) complex. A highly stereoselective, three-component direct Mannich reaction of ketone 34, benzaldehyde, and p-toluenesulfonamide using bifunctional catalyst 36 was developed (Org. Lett. 2013, 15, 508. ) by John Cong-Gui Zhao at the University of Texas at San Antonio.
Tomislav Rovis at Colorado State University reported (J. Am. Chem. Soc. 2013, 135, 8504. ) that the novel N-heterocyclic carbene 39 catalyzed the asymmetric intermolecular reaction of enal 37 and nitroalkene 38 to yield δ-nitroester 40. Last but not least, Yungui Peng at Southwest University in China reported (Chem. Commun. 2013, 49, 4561. ) that the chiral pyrrolidine 42 catalyzed the Michael reaction of aldehyde 41 with nitroolefin 43 to produce γ-nitrocarbonyl 44 with high ee and dr.
L. Benkoski, T. H. Lambert, Org. Chem. Highlights 2014, February 24.