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Monday, February 29, 2016
Douglass F. Taber
University of Delaware

Organic Functional Group Interconversion

Jalil Noei of Islamic Azad University and Arsalan Mirjafari of Florida Gulf Coast University observed (Tetrahedron Lett. 2014, 55, 4424. ) smooth conversion of a methoxymethyl ether 1 to the iodide 2. A related protocol could be used to directly prepare the corresponding nitrile (not illustrated). Chao-Jun Li of McGill University showed (Tetrahedron Lett. 2015, 56, 1699. ) that ultraviolet light significantly accelerated the rate of elimination of an alkyl iodide 3 to the alkene 4.

Johannes G. de Vries of the Leibniz-Institüt für Katalyse and Edwin Otten of the University of Groningen used (Angew. Chem. Int. Ed. 2015, 54, 4236. ) a Ru catalyst to prepare 7 by the addition of the alcohol 6 to the unsaturated nitrile 5. Tobias Ritter of Harvard University established (Angew. Chem. Int. Ed. 2015, 54, 5662. ) that the coupling of the phenol 9 with the alcohol 8 gave 10 with clean inversion of configuration. Soon Hyeok Hong of Seoul National University used (J. Org. Chem. 2015, 80, 4152. ) an Ir-catalyzed borrowed hydrogen approach to prepare the lactam 13 by combining the amine 12 with the lactone 11.

The Wharton arrangement has long been used to convert an epoxy ketone to the allylic alcohol. Christopher D. Maycock of the Universidade de Lisboa described (J. Org. Chem. 2015, 80, 3067. ) the aza version of this rearrangement, converting the aziridine 14 into the allylic amine 15. This reaction is likely proceeding via an intermediate alkenyl radical at the site indicated, that might be induced to participate in an intramolecular cyclization.

Toshio Nishikawa of Nagoya University developed (Chem. Asian. J. 2015, 10, 1035. ) mild conditions for hydrolyzing a gem dibromide 16 to the ketone 17. Xihe Bi of Northeast Normal University devised (Org. Lett. 2014, 16, 3668. ) a general procedure for the conversion of a terminal alkyne 18 to the alkenyl azide 19. Gerald B. Hammond and Bo Xu of the University of Louisville showed (Org. Lett. 2015, 17, 162. ) that the gold nanoparticles they developed for the hydration of a terminal alkyne 20 to the ketone 21 could be recycled by simple filtration and reused. José F. Quílez del Moral and Alejandro F. Barrero of the University of Granada found (Eur. J. Org. Chem. 2015, 3266. ) that the dehydration of the ketone 22 to the terminal alkyne 23 was best carried out over two steps.

Louis Barriault of the University of Ottawa prepared (J. Org. Chem. 2015, 80, 2874. ) the amide 26 by coupling 25 with 24, activated by the in situ generation of the Vilsmeier-Haack reagent. Lei Liu of Tsinghua University showed (Angew. Chem. Int. Ed. 2015, 54, 2194. ) that 27 could be oxidized to the acylating agent 28 in the presence of the attached deprotected peptide. Professor Liu also developed (Angew. Chem. Int. Ed. 2015, 54, 5713. ) 31, prepared by combining 29 with 30, as a protected form of N-terminal cysteine. This could be carried through three steps of native chemical ligation before being deprotected to use in the fourth such step.

As an alternative to sulfur-mediated peptide coupling, Paramjit S. Arora of New York University devised (J. Am. Chem. Soc. 2015, 137, 6932. ) an o-selenyl aldehyde that could be generated in situ from the corresponding diselenide and used to prepare, inter alia, the acylating agent 32. An amine such as 33 then added readily to the aldehyde, to give an intermediate that proceeded by intramolecular acylation to form the coupled product 34.

D. F. Taber, Org. Chem. Highlights 2016, February 29.
URL: http://www.organic-chemistry.org/Highlights/2016/29February.shtm