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Monday, July 12, 2010
Douglass F. Taber
University of Delaware

Enantioselective Preparation of Alcohols and Amines

Renat Kadyrov of Evonik Degussa and Magnus Rueping of RWTH Aachen developed (Angew. Chem. Int. Ed. 2009, 49, 7556. ) an effective catalyst for the enantioselective hydrogenation of an α-hydroxy ketone 1 to the 1,2-diol 2. Yong-Gui Zhou of the Dalian Institute of Chemical Physics showed (J. Org. Chem. 2009, 74, 5633. ) that a sultam such as 3 could be reduced with high ee to the sulfonamide 4. They also used this same approach to prepare both α-aryl and α,α-diaryl amines.

David W. C. MacMillan of Princeton University described (Angew. Chem. Int. Ed. 2009, 49, 5121. ) the optimized enantioselective α-chlorination of an aldehyde 5 and the direct processing of the product to the epoxide 6. Erick M. Carreira of ETH Zürich reported (Synlett 2009, 2076. ) an alternative route to high ee epoxides by decarbonylation of an epoxy aldehyde 7. James P. Morken of Boston College established (J. Am. Chem. Soc. 2009, 131, 13210. ) a procedure for the enantioselective bis borylation of a terminal alkene 9, leading after oxidation to the 1,2-diol 10. Ben L. Feringa of the University of Groningen took advantage (J. Am. Chem. Soc. 2009, 131, 9473. ) of their alternative Wacker conditions to convert a primary allylic carbonate 11 to the protected β-amino aldehyde12.

Chao-Shan Da of Lanzhou University devised (Org. Lett. 2009, 11, 5578. ) additives that allow the direct enantioselective addition of a Grignard reagent 14 to an aldehyde. The enantioselective addition of substituted ketenes to aldehydes has long been established. Yun-Ming Lin of the University of Toledo developed (Synlett 2009, 1675. ) a catalyst system for the enantioselective addition of ketene 17 itself. An alkenyl silane 19 can readily be prepared from the corresponding terminal alkene (J. Org. Chem. 2010, 75, 1701. ). Koichi Mikami of the Tokyo Institute of Technology showed (J. Am. Chem. Soc. 2009, 131, 13922. ). that such alkenyl silanes add to ethyl glyoxylate 20 with high ee.

Amir H. Hoveyda of Boston College devised (J. Am. Chem. Soc. 2009, 131, 18234. ) a procedure for the enantioselective conversion of a terminal alkyne 22 to the 1,2-bis boryl alkane, that he took on directly to the coupled product 24. Note that these are the same sort of 1,2-bis boryl alkanes as those described by Professor Morken in the conversion of 9 to 10.

Luca Bernardi and Alfredo Ricci of the University of Bologna optimized (Angew. Chem. Int. Ed. 2009, 49, 5694. ) a quinidine-based catalyst for the enantioselective addition of the commercial 26 to the aldehyde derivative 25 to give the β-amido ester 27. Géraldine Masson and Jieping Zhu of Gif-sur-Yvette reported (Org. Lett. 2009, 11, 4648. ) a related catalyst for the enantioselective aza-Morita-Baylis-Hillman addition of 29 to the imine 28. Eric N. Jacobsen of Harvard University developed (Nature 2009, 461, 968. ) a practical procedure for the Strecker cyanation of the pivaldehyde imine 31. Andrew D. Smith of the University of St. Andrews designed (Angew. Chem. Int. Ed. 2009, 49, 8914. ) an organocatalyst for the enantioselective rearrangement of 33 to 34.

D. F. Taber, Org. Chem. Highlights 2010, July 12.