Organic Chemistry Portal
Organic Chemistry Highlights

Monday, May 16, 2016
Douglass F. Taber
University of Delaware

Reduction: The Inoue Synthesis of 14, 20-DDHA

Naseem Ahmed of the Indian Institute of Technology Roorkee observed (Tetrahedron Lett. 2015, 56, 6202. DOI: 10.1016/j.tetlet.2015.09.083) that an epoxide 1 can be deoxygenated to the alkene 2 by warming with polyphosphoric acid. Stefan Grimme of the Universität Bonn and Douglas W. Stephan of the University of Toronto found (Angew. Chem. Int. Ed. 2015, 54, 8250. DOI: 10.1002/anie.201502579) that a phosphonium cation could catalyze the reduction of a ketone 3 to the hydrocarbon 4.

David A. Nicewicz of the University of North Carolina developed (J. Am. Chem. Soc. 2015, 137, 11340. DOI: 10.1021/jacs.5b07770) an acridinium catalyst that mediated the reductive decarboxylation of a carboxylic acid 5 to the hydrocarbon 6. Dennis P. Curran of the University of Pittsburgh showed (J. Am. Chem. Soc. 2015, 137, 8617. DOI: 10.1021/jacs.5b04677) that the carbene borane 8 under free radical conditions removed a cyano group from 7, leading to 9.

Bill Morandi of the Max-Planck-Institut für Kohlenforschung selectively deoxygenated (Angew. Chem. Int. Ed. 2015, 54, 8814. DOI: 10.1002/anie.201503172) the diol 10, leading to the protected secondary alcohol 11. Craig J. Hawker and Javier Read de Alaniz of the University of California, Santa Barbara devised (Chem. Commun. 2015, 51, 11705. DOI: 10.1039/C5CC04677G) 10-phenylphenothiazine as a photocatalyst for the radical dehalogenation of 12 to 13. Zhimin Liu of Institute of Chemistry of the Chinese Academy of Sciences found (Chem. Commun. 2015, 51, 12212. DOI: 10.1039/C5CC03563E) that both phenols such as 14 (leading to 15) and aryl ethers could be deoxygenated with a combination of K t-butoxide and LiAlH4 at elevated temperature.

Rhett Kempe of the Universität Bayreuth optimized (J. Am. Chem. Soc. 2015, 137, 7998. DOI: 10.1021/jacs.5b04349) a Co catalyst for the selective hydrogenation of 16 to 17. Similarly, Zheng Huang of the Shanghai Institute of Organic Chemistry selectively reduced the unsaturated ester 18 to the alkenyl alcohol 19 (Chem. Eur. J. 2015, 21, 14737. DOI: 10.1002/chem.201502942).

1-Decalones such as 20 are often an equilibrium mixture of cis- and trans-fused diastereomers. Nicole Kennedy and Theodore Cohen, also of the University of Pittsburgh, observed (J. Org. Chem. 2015, 80, 8134. DOI: 10.1021/acs.joc.5b01232) that the reduction of the presumably equilibrating 20 led to 21 as the dominant diastereomer.

Norio Sakai of the Tokyo University of Science established (Tetrahedron Lett. 2015, 56, 6448. DOI: 10.1016/j.tetlet.2015.09.148) a simple reagent combination for the reduction of a secondary amide 22 to the amine 23. Aaron D. Sadow of Iowa State University reported (ACS Catal. 2015, 5, 4219. DOI: 10.1021/acscatal.5b01038) a parallel study (not illustrated). Maurizio Benaglia of the Università degli Studi di Milano was able (Org. Lett. 2015, 17, 3941. DOI: 10.1021/acs.orglett.5b01698) to reduce the nitro group of 24 selectively to the amine 25.

Masayuki Inoue of the University of Tokyo observed (J. Org. Chem. 2015, 80, 7713. DOI: 10.1021/acs.joc.5b01461) that a 14, 20-dihydroxy metabolite 28 of docosahexaenoic acid inhibited infiltration of polymorphonuclear leukocytes at nanomolar concentrations. En route to 28, he found that the last alkyne of 26 reduced only sluggishly. He solved this problem with the Isobe protocol, preparing the Co2(CO)8 complex of the monoyne and reducing it with Bu3SnH.

D. F. Taber, Org. Chem. Highlights 2016, May 16.