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Monday, November 12, 2012
Douglass F. Taber
University of Delaware

Functional Group Oxidation and Reduction

Debabrata Maiti of the Indian Institute of Technology Bombay found (Chem. Commun. 2012, 48, 4253. ) that the relatively inexpensive Pd(OAc)2 effectively catalyzed the decarbonylation of an aldehyde 1 to the hydrocarbon 2. Hui Lou of Zhejiang University used (Adv. Synth. Catal. 2011, 353, 2577. ) a Mo catalyst to effect reduction of the ester 3 to the hydrocarbon 4, with retention of all the skeletal carbons.

Jon T. Njardarson of the University of Arizona showed (Chem. Commun. 2012, 48, 7844. ) that the allylic ether 5 could be reduced with high regioselectivity, to give 6. José Barluenga and Carlos Valdés of the Universidad de Oviedo effected (Angew. Chem. Int. Ed. 2012, 51, 5950. ) the direct conversion of a ketone 7 to the azide 8. Although no cyclic ketones were included in the examples, there is a good chance that this will be the long-sought diastereoselective reduction of a cyclohexanone to the equatorial amine.

Hideo Nagashima of Kyushu University reduced (Chem. Lett. 2012, 41, 229. ) the acid 9 directly to the aldehyde 1 using a ruthenium catalyst with the bis silane 10. Georgii I. Nikonov of Brock University described (Adv. Synth. Catal. 2012, 354, 607. ) a similar Ru-mediated silane reduction of an acid chloride to the aldehyde. Professor Nagashima used (Angew. Chem. Int. Ed. 2012, 51, 5363. ) his same Ru catalyst to reduce the ester 11 to the protected amine 12.

Shmaryahu Hoz of Bar-Ilan University used (J. Org. Chem. 2012, 77, 4029. ) photostimulation to promote the SmI2-mediated reduction of a nitrile 13 to the amine 14. Bakthan Singaram of the University of California, Santa Cruz effected (J. Org. Chem. 2012, 77, 221. ) the same transformation with InCl3/NaBH4. David J. Procter of the University of Manchester described (J. Org. Chem. 2012, 77, 3049. ) what promises to be a general method for activating Sm metal to form SmI2. Mark T. Hamann of the University of Mississippi directly reduced (J. Org. Chem. 2012, 77, 4578. ) the nitro group of 15 to the alkylated amine 16.

Cleanly oxidizing aromatic methyl groups to the level of the aldehyde without overoxidation has been a challenge. K. S. Rangappa of the University of Mysore devised (Tetrahedron Lett. 2012, 53, 2632. ) a simple solution to this problem, converting 17 to the oxime 18. Yoel Sasson of the Hebrew University of Jerusalem showed (Tetrahedron Lett. 2012, 53, 2295. ) that K3PO4 was effective for full dehydrobromination of the dibromide from 19 to the alkyne 20.

Yoshiharu Iwabuchi of Tohoku University oxidized (Org. Lett. 2012, 14, 154. ) the silyl enol ether 21 to the enone 23 with the stoichiometric reagent 22. Anne E. V. Gorden of Auburn University optimized (J. Org. Chem. 2012, 77, 4628. ) a Cu catalyst for the allylic oxidation of 24 to 25. Patrizia Gentili of the Università degli Studi La Sapienza oxidized (Chem. Commun. 2012, 48, 5358. ) the aldehyde 1 to the oxime 26 using stoichiometric NaNO2/FeCl3. Masahiro Murakami of Kyoto University transformed (J. Am. Chem. Soc. 2012, 134, 194. ) the alkyne 27 into the α-sulfonamido ketone 28 by Rh-mediated hydration of the intermediate triazole, from the Cu-catalyzed addition of TsN3.

Readers may be interested in the Nozoe autograph book project, currently underway (free access: Chem. Rec. 2012, 12, 517. ) under the editorship of Jeffrey I. Seeman of the University of Richmond.

D. F. Taber, Org. Chem. Highlights 2012, November 12.