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Monday, September 20, 2010
Douglass F. Taber
University of Delaware

Alkene Reactions: The Dabdoub/Baroni Synthesis of (±)-Dihydroactinidiolide

David B. Cordes of Pacific University reported (Tetrahedron Lett. 2009, 50, 1817. ) a simple combination of NaBH4 and Pd/C that reduced the alkene 1 to 2. This could be particularly welcome as a method for deuteration. Following up on the work of He (Selective Reactions of Alkenes 2006, February 27), Makoto Tokunaga of Kyushu University found (Tetrahedron Lett. 2009, 50, 5510. ) that chloroethanol (4) worked particularly well for the Au-catalyzed alkoxylation of the alkene 3.

It has been difficult to achieve high regiocontrol in the Wacker oxidation of oxygen-substituted alkenes such as 6. Matthew S. Sigman of the University of Utah devised (J. Am. Chem. Soc. 2009, 131, 6076. ) a ligand for Pd that gave clean conversion to 7. Huanfeng Jiang of the South China University of Technology found (J. Am. Chem. Soc. 2009, 131, 3846. ) that under oxidizing conditions, a Pd catalyst could effect the diacetoxylation of 8, to give 9.

Bernhard Breit of Albert-Ludwigs-Universität, Freiburg designed (Angew. Chem. Int. Ed. 2009, 48, 8022. ) a Rh catalyst for tandem linear hydroformylation and in situ reduction of the resulting aldehyde, converting the alkene 3 into the primary alcohol 10. Erick M. Carreira of ETH Zürich established (J. Am. Chem. Soc. 2009, 131, 13214. ) that under Co catalysis, 12 could be added to an alkene 11 in a branching sense. The resulting product could, inter alia, be reduced to the aldehyde 13.

In the course of a synthesis of the natural amino acid tetrahydrolathyrine, Josiane Thierry and Robert H. Dodd of CNRS Gif-sur-Yvette employed (J. Org. Chem. 2009, 74, 5331. ) tandem aziridination/cyanide opening to effect homologation of the alkene 14 to 15. Sensuke Ogoshi of Osaka University demonstrated (J. Am. Chem. Soc. 2009, 131, 10350. ) that a Ni catalyst could effect conjugate addition of an alkene 16 to the enone 17. Yoichiro Koninobu and Kazuhiko Takai of Okayama University observed (J. Am. Chem. Soc. 2009, 131, 9914. ) that a Re catalyst could effect o-selective addition of an alkene 3 to a phenol 19. Even though allylic esters such as 21 are sensitive to Pd catalysis, Carlos Roque Duarte Correia of the Universidade Estadual de Campinas found conditions (Org. Lett. 2009, 11, 3642. ) for the Heck addition of an arene diazonium salt 22, to give 23.

The conversion of 8 to 9 and of 14 to 15 are examples of reactions that functionalize both ends of an alkene. Miguel J. Dabdoub of the Universidade de São Paulo and Adriano C. M. Baroni of the Universidade Federal do Mato Grosso do Sul took advantage (Tetrahedron Lett. 2009, 50, 5569. ) of another such transformation, the addition of the chloro ester 25 to 24 to give the lactone 26, in a short synthesis of the Solenopsis invicta pheromone (±)-Dihydroactinidiolide (27).

D. F. Taber, Org. Chem. Highlights 2010, September 20.