Arrays of Stereogenic Centers: The Davies Synthesis of Acosamine
Babak Borhan of Michigan State University found (Angew. Chem. Int. Ed. 2011, 50, 2593. ) that the ligand developed for asymmetric osmylation worked well for the enantioselective cyclization of 1 to 2. Kyungsoo Oh of IUPUI devised (Org. Lett. 2011, 13, 1306. ) a Co catalyst for the stereocontrolled addition of 4 to 3, to give 5. Michael J. Krische of UT Austin prepared (Angew. Chem. Int. Ed. 2011, 50, 3493. ) 8 by Ir* mediated oxidation/addition of 7 to 6. Yixin Lu of the National University of Singapore employed (Angew. Chem. Int. Ed. 2011, 50, 1861. ) an organocatalyst to effect stereocontrolled addition of 10 to 9.
Naoya Kumagai and Masakatsu Shibasaki of the Insitute of Microbial Chemistry, Tokyo took advantage (J. Am. Chem. Soc. 2011, 133, 5554. ) of the soft Lewis basicity of 13 to effect stereocontrolled condensation with 12. Yujiro Hayashi of the Tokyo University of Science found (Angew. Chem. Int. Ed. 2011, 50, 2804, not illustrated. ) that aqueous chloroacetaldehyde participated well in crossed aldol reactions. Andrew V. Malkov, now at Loughborough University, and Pavel Kocovsky of the University of Glasgow showed (J. Org. Chem. 2011, 76, 4800. ) that the inexpensive mixed crotyl silane 16 could be added to 15 with high stereocontrol. Shigeki Matsunaga of the University of Tokyo and Professor Shibasaki opened (J. Am. Chem. Soc. 2011, 133, 5791. ) the meso aziridine 18 with malonate 19 to give 20. Masahiro Terada of Tohoku University effected (Org. Lett. 2011, 13, 2026. ) conjugate addition of 22 to 21 with high stereocontrol. Jinxing Ye of the East China University of Science and Technology reported (Angew. Chem. Int. Ed. 2011, 50, 3232, not illustrated. ) a related conjugate addition.
Kian L. Tian of Boston College observed (Org. Lett. 2011, 13, 2686. ) that the kinetic hydroformylation of 24 set the relative configuration of two stereogenic centers. Alexandre Alexakis and Clément Mazet of the Université de Genève established (Angew. Chem. Int. Ed. 2011, 50, 2354. ) a tandem one-pot procedure for the addition of 26 to 27 to give 28. Eric N. Jacobsen of Harvard University designed (J. Am. Chem. Soc. 2011, 133, 5062. ) an organocatalyst that directed the absolute sense of the Claisen rearrangement of 29 to 30. Professor Ye also designed (Org. Lett. 2011, 13, 564. ) the conjugate addition of 31 to 32, to give 33.
Stephen G. Davies of the University of Oxford observed (Tetrahedron Lett. 2011, 52, 2216. ) that epoxidation of the amine derived from conjugate addition of 35 to methyl sorbate 34 proceeded with high diastereoselectivity. The product 36 was carried on to the protected Acosamine derivative 37.