C-C Bond Construction: The Galano Synthesis of 8-F3t-Isoprostane
Nobuaki Kambe of Osaka University devised (Synthesis 2014, 46, 1583. DOI: 10.1055/s-0033-1341152) simple conditions for coupling an alkyl halide 1 with a Grignard reagent 2, leading to 3. Michael J. Chetcuti and Vincent Ritleng of the Université de Strasbourg arylated (Chem. Commun. 2014, 50, 4624. DOI: 10.1039/C4CC00959B) the ketone 4 with 5 to give 6. Ilhyong Ryu of Osaka Prefecture University effected (J. Org. Chem. 2014, 79, 3999. DOI: 10.1021/jo500464q) net conjugate acylation of the enone 8 by reducing 7 in the presence of carbon monoxide. Yasushi Obora of Kansai University employed (Chem. Commun. 2014, 50, 2491. DOI: 10.1039/C3CC49626K) a borrowed hydrogen strategy to effect the net methylation of nitrile 10 to 11. There have been many examples of the alkylation of ketones using variations on this strategy.
Robert H. Grubbs and Brian M. Stoltz of Caltech decarboxylated (Adv. Synth. Catal. 2014, 356, 130. DOI: 10.1002/adsc.201301109) an acid 12 to the corresponding alpha olefin 13. Lindsey O. Davis of Berry College combined (Tetrahedron Lett. 2014, 55, 3100. DOI: 10.1016/j.tetlet.2014.04.002) the imine 14 with the aldehyde 15 in the presence of 16 to give the enone 17. Masahiro Miyazawa of the University of Toyoma maintained (Synlett 2014, 25, 531. DOI: 10.1055/s-0033-1340477) the geometric purity of 18 while coupling it with Me3Al to give the diene 19. Naoki Kanoh of Tohoku University used (Eur. J. Org. Chem. 2014, 1376. DOI: 10.1002/ejoc.201301487) the Micalizio protocol to add 22 to 20 to give the triene 23.
Xile Hu of the Ecole Polytechnique Fédérale de Lausanne coupled (Org. Lett. 2014, 16, 2566. DOI: 10.1021/ol501087m) 25 with the iodide 24 to give the alkyne 26. Keiji Tanino of Hokkaido University prepared (Tetrahedron Lett. 2014, 55, 1097. DOI: 10.1016/j.tetlet.2013.12.096) the α-quaternary alkyne 29 by 1,2-addition of 28 to the ketone 27 followed by pinacol rearrangement.
Zhaoguo Zhang of Shanghai Jiao Tong University and Tahar Ayad and Virginie Ratovelomanana-Vidal of Chimie ParisTech coupled (ACS Catal. 2014, 4, 44. DOI: 10.1021/cs4007827) 31 with the dienyl bromide 30 to deliver the disubstituted allene 32 in high ee. Amir H. Hoveyda of Boston College developed (Angew. Chem. Int. Ed. 2013, 52, 7694. DOI: 10.1002/anie.201303501) a procedure for the preparation of alkynes such as 33 in substantial ee. He showed that 33 could be isomerized to the corresponding trisubstituted allene 34 with mainentance of the ee.
The isoprostanes and neuroprostanes, products of non-enzymatic oxidation of essential fatty acids, have physiologically-important receptors in the human body. Facing difficulty in assembling the upper sidechain of 8-F3t-Isoprostane (37), Jean-Marie Galano of University Montpellier I and II turned (Chem. Eur. J. 2014, 20, 6374. DOI: 10.1002/chem.201400380) to alkyne metathesis. Indeed, 35 readily cyclized to 36, that was carried on to 37.