C-H Bond Functionalization: The Vanderwal/Alexanian Synthesis of Chlorolissoclimide

Alexander Breder of the Georg-August-Universität Göttingen developed (Org. Lett. 2016, 18, 2856. DOI: 10.1021/acs.orglett.6b01130) a protocol for the photochemically-promoted oxidation of 1 to 2. M. Christina White of the University of Illinois found (J. Am. Chem. Soc. 2016, 138, 1265. DOI: 10.1021/jacs.5b11294) that with a Co-mediated recycling of the benzoquinone oxidant, 5 could be prepared by the coupling of 3 with 4. Guangbin Dong of the University of Texas achieved (Angew. Chem. Int. Ed. 2016, 55, 5299. DOI: 10.1002/anie.201600912) selective oxidation of the amine 6 to 7. Gong Chen, now at Nankai University, used (Chem. Sci. 2016, 7, 2679. DOI: 10.1039/C5SC04169D) 9 to effect the selective chlorination of 8 to 10. Azides and bromides were also prepared by variations in the procedure.

Masahiro Murakami of Kyoto University selectively carboxylated (Chem. Eur. J. 2016, 22, 6524. DOI: 10.1002/chem.201600682) 11 to give 12. Aiwen Lei of Wuhan University coupled (Nature Commun. 2016, 7, 11676. DOI: 10.1038/ncomms11676) 13 with 14 to give 15. Xiao-Feng Wu of the Universität Rostock observed (Angew. Chem. Int. Ed. 2016, 55, 7227. DOI: 10.1002/anie.201603235) high regioselectivity in the carboxylation of 16 with 17 and CO to give 18. Haibo Ge of Indiana University-Purdue University Indianapolis (IUPUI) used (Chem. Sci. 2016, 7, 2804. DOI: 10.1039/C5SC04066C) a directing group to guide a Pd-catalyzed double C-H functionalization, coupling 19 with acetonitrile 20 to selectively give 21. Yu Rao of Tsinghua University assembled (Tetrahedron Lett. 2016, 57, 819. DOI: 10.1016/j.tetlet.2016.01.009) a useful overview of directing group guided transition metal-mediated C-H functionalization.

Daniel Solé of the Universitat de Barcelona and Israel Fernández of the Universidad Complutense de Madrid found (Angew. Chem. Int. Ed. 2016, 55, 6467. DOI: 10.1002/anie.201602020) that a Pd catalyst was effective for the cyclization of 22 to pyrrolidine 23. Richard J. K. Taylor and William P. Unsworth of the University of York took advantage (Org. Biomol. Chem. 2016, 14, 1641. DOI: 10.1039/C5OB02579F) of the preference of Rh-mediated insertion to select for equatorial C-H bonds, converting 24 to α-cylocostunolide (25).

Liming Zhang of the University of California, Santa Barbara devised (J. Am. Chem. Soc. 2016, 138, 7516. DOI: 10.1021/jacs.6b04297) a new approach to alkylidene carbenes, cyclizing 26 to 27. Masahiro Anada of Hokkaido University showed (Tetrahedron 2016, 72, 3939. DOI: 10.1016/j.tet.2016.05.015) that the Hashimoto catalyst was effective for cyclizing the prochiral 28 to 29 in high ee.

In a collaborative effort, Christopher D. Vanderwal of the University of California, Irvine and Erik J. Alexanian of the University of North Carolina effected (J. Am. Chem. Soc. 2016, 138, 696. DOI: 10.1021/jacs.5b12308) the highly selective chlorination of commercial sclareolide 30. The product 32 was carried on to the cytotoxic chlorolissoclimide (33).