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Monday, November 14, 2011
Douglass F. Taber
University of Delaware

Organic Functional Group Protection and Deprotection

Corey R. J. Stephenson of Boston University devised (Chem. Commun. 2011, 47, 5040. ) a protocol using visible light for removing the PMB group from 1 to give 2. John F. Hartwig, now at the University of California, Berkeley developed (Science 2011, 332, 439. ) a Ni catalyst for the cleavage of the durable aryl ether of 3 to give 4. Mark S. Taylor of the University of Toronto devised (J. Am. Chem. Soc. 2011, 133, 3724. ) the catalyst 6, that selectively mediated esterification of 5 to 7. Jean-Marie Beau of the Université Paris-Sud added (Chem. Commun. 2011, 47, 2146. ) Et3SiH following the Fe-catalyzed deprotection-protection of 8, resulting in clean conversion to the bis ether 9.

Mahmood Tajbakhsh of the University of Mazandaran showed (Tetrahedron Lett. 2011, 52, 1260. ) that guanidine HCl catalyzed the conversion of 10 to 11. Stephen W. Wright of Pfizer/Groton established (Tetrahedron Lett. 2011, 52, 3171. ) that the new urethane protecting group of 12, stable to many conditions, could be deprotected to 13 under conditions that spared even a Boc group. Matthias Beller of the Leibniz-Institute for Catalysis protected (Chem. Commun. 2011, 47, 2152. ) the amine 14 as the readily-hydrolyzed imidazole 16. Sentaro Okamoto of Kanagawa University found (Org. Lett. 2011, 13, 2626. ) a simple reagent combination for the removal of the sometimes reluctant sulfonamide from 17.

Jordi Burés and Jaume Vilarrasa of the Universitat de Barcelona removed (Angew. Chem. Int. Ed. 2011, 50, 3275. ) the oxime from 19 by Au-catalyzed exchange with 20. Pengfei Wang of the University of Alabama, Birmingham designed (J. Org. Chem. 2011, 76, 2040. ) a range of photochemically-removable protecting groups for aldehydes and ketones.

Rafael Robles of the University of Granada selectively protected (J. Org. Chem. 2011, 76, 2277. ) the diol 24 using the reagent created by the activation of 25. Berit Olofsson of Stockholm University prepared (Org. Lett. 2011, 13, 3462. ) the phenyl ester 28 by exposing 27 to the diaryl iodonium triflate. Kannoth Manheri Muraleedharan of the Indian Institute of Technology, Madras selectively (Org. Lett. 2011, 13, 1932. ) esterified 29 to 30 with catalytic SmCl3.

Amides are usually more resistant than esters to hydrolysis. Bruce Ganem of Cornell University removed (Tetrahedron Lett. 2011, 52, 2209. ) the t-butyl amide of 31 in the presence of the usually much more fragile acetate, to deliver 32.

D. F. Taber, Org. Chem. Highlights 2011, November 14.