Selective Functionalization of C-H Bonds
Jianhui Huang and Kang Zhao of Tianjin University devised (Chem. Commun. 2013, 49, 1211. DOI: 10.1039/C2CC37779A) a protocol for the oxidation of a terminal alkene 1 to the valuable four-carbon synthon 2. M. Christina White of the University of Illinois effected (J. Am. Chem. Soc. 2013, 135, 7831. DOI: 10.1021/ja402651q) the oxidation of the terminal alkene 3 to the enone 4. Miquel Costas of the Universitat de Girona developed (J. Org. Chem. 2013, 78, 1421, DOI: 10.1021/jo302196q; Chem. Eur. J. 2013, 19, 1908, DOI: 10.1002/chem.201203281) a family of Fe catalysts for the oxidation of methylenes to ketones. Depending on the catalyst, any of the three ketones from the oxidation of 5 could be made the dominant product.
Yumei Xiao and Zhaohai Qin of China Agricultural University optimized (Synthesis 2013, 45, 615. DOI: 10.1055/s-0032-1318172) the Co-catalyzed oxidation of the methyl group of 7 to the aldehyde. Thanh Binh Nguyen of CNRS Gif-sur-Yvette established (J. Am. Chem. Soc. 2013, 135, 118. DOI: 10.1021/ja311780a) a protocol (not illustrated) for the oxidation of methyl groups on heteroaromatics.
Shunsuke Chiba of Nanyang Technological University cyclized (Org. Lett. 2013, 15, 212, 3214. DOI: 10.1021/ol303302r) the amidine 9 to 10, and the hydrazone 11 to 12. These cyclizations proceeded by sequential C-H abstraction followed by recombination, and so were racemizing. In contrast, the conversion of 13 to 14, developed (Science 2013, 340, 591. DOI: 10.1126/science.1233701) by Theodore A. Betley of Harvard University, proceeded with substantial retention of absolute configuration.
Tsutomu Katsuki of Kyushu University designed (Angew. Chem. Int. Ed. 2013, 52, 1739. DOI: 10.1002/anie.201208906) a Ru catalyst that was selective for the allylic position of the E-alkene 15. Amination was highly regioselective, and proceeded with excellent ee.
Ilhyong Ryu of Osaka Prefecture University and Maurizio Fagnoni of the University of Pavia reported (Org. Lett. 2013, 15, 2554. DOI: 10.1021/ol401061v) the direct carbonylation of 17 to the amide 18. David W. C. MacMillan of Princeton University devised (Science 2013, 339, 1593. DOI: 10.1126/science.1232993) a protocol for the β-arylation of an aldehyde 19 to give 20.
Directed palladation of distal C-H bonds continues to be developed. Srinivasarao Arulananda Babu of the Indian Institute of Science Education and Research effected (Org. Lett. 2013, 15, 3238. DOI: 10.1021/ol4012212) diastereoselective arylation of the cyclopropane 21 to give 22. M. Ángeles Fernández-Ibáñez and Juan C. Carretero of the Universidad Autónoma de Madrid showed (Chem. Sci. 2013, 4, 175. DOI: 10.1039/C2SC21162A) that the pyridylsulfonamide of 24 was an effective directing group. Jin-Quan Yu of Scripps/La Jolla devised (J. Am. Chem. Soc. 2013, 135, 3387. DOI: 10.1021/ja400648w) a protocol for the direct alkynylation of 27. Gong Chen of Pennsylvania State University established (J. Am. Chem. Soc. 2013, 135, 2124. DOI: 10.1021/ja312277g) conditions for sp3-sp3 coupling, converting 30 into 32.