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Monday, March 26, 2018
Douglass F. Taber
University of Delaware

Functional Group Reduction

Yuanzhi Xia of Wenzhou University combined (J. Org. Chem. 2017, 82, 1340. ) 2-propanol (2) with a Ru catalyst to reduce 1 to 3. Jianbo Wang of Peking University converted (J. Org. Chem. 2017, 82, 624. ) the aldehyde 4 to the stannane 5, by way of the intermediate unstablized diazo alkane (not illustrated). Martin Oestreich of the Technische Universitńt Berlin reduced (Angew. Chem. Int. Ed. 2017, 56, 3389. ) the tosylate 6 to 7, a reminder that this (Tetrahedron Lett. 1999, 40, 8919. ) is one of the milder protocols for deprotecting an alkylated phenol. Jun Okuda of RWTH Aachen University used (Chem. Commun. 2017, 53, 3493. ) stoichiometric 9 in the presence of an Al catalyst to reduce the cyclic ether 8 to the alcohol 10.

Thanh V. Nguyen of the University of New South Wales converted (Org. Lett. 2017, 19, 1398. ) the ketone 11 directly to the silyl ether 12. Bo Xu of Donghua University showed (Chem. Asian J. 2017, 12, 190. ) that even very reactive reagents such as LiAlH4 could be incorporated into water-stable tablets. On combining with an organic solvent, the tablet released the reagent to reduce 13 to 14. In a parallel development, Warren C. W. Chan of the University of Toronto described (J. Am. Chem. Soc. 2017, 139, 17341. ) simplifying assays by tableting reagents.

Antony J. Fairbanks of the University of Canterbury observed (Chem. Commun. 2017, 53, 713. ) that NaI in the presence of an acidic ion exchange resin was sufficient to reduce an azide 15 to the amine 16. Neil K. Garg of UCLA developed (Org. Lett. 2017, 19, 1910. ) a Ni catalyst for the reduction of an amide 17 to the amine 18. Michael J. Ingleson of the University of Manchester established (Chem. Eur. J. 2017, 23, 2217. ) that the reductive amination of 19 with 20 to give 21 was tolerant of water. Norio Sakai of the Tokyo University of Science effected (Eur. J. Org. Chem. 2017, 2866. ) the conversion of the secondary amine 23 to the tertiary amine 24, using the secondary amide 22 as the alkylating agent.

Nicholas J. Harmer of the University of Exeter reported (ChemCatChem 2017, 9, 1005. ) the use of an enzyme to reduce an acid 25 to the aldehyde 26. Professor Sakai reduced (J. Org. Chem. 2017, 82, 3659. ) the acid 27 in the presence of 28, leading to the thioacetal 29. Goutam Kumar Lahiri and Debabrata Maiti of the Indian Institute of Technology Bombay removed (ACS Catal. 2017, 7, 433. ) the amide from 30 to give 31. Magnus Rueping, also of RWTH Aachen University, described (Angew. Chem. Int. Ed. 2017, 56, 3972. ) a parallel investigation (not illustrated).

Polyunsaturated fatty acids (PUFA) such as arachidonic acid (32) are essential to human health, as they are transformed in vivo into locally acting hormones, including prostaglandins and thromboxanes. Stable isotope labeled analogs such as 33, important for biochemical studies, have in the past been available only by multi-step chemical synthesis. M. S. Shchepinov of Retrotope and D. VidovÝc of Monash University found (J. Org. Chem. 2017, 82, 13115. ) that an easily-prepared Ru catalyst exchanged the doubly-allylic methylenes of 32 without erosion of alkene geometry.

D. F. Taber, Org. Chem. Highlights 2017, March 26.
URL: https://www.organic-chemistry.org/Highlights/2018/26March.shtm