Synthesis of cyclohexanes
A rhodium-catalyzed transfer hydrogenation of functionalized arenes in the presence of tetrahydroxydiboron offers good functional group tolerance, operational simplicity and controllable chemoselectivity. The general applicability of this procedure is demonstrated by the selective hydrogenation of a range of arenes, including functionalized benzenes, biphenyls, and polyaromatics.
Y. Wang, Z. Chang, Y. Hu, X. Lin, X. Dou, Org. Lett., 2021, 23, 1910-1914.
CuCl2 catalyzes a coupling of unactivated C(sp3)-H bonds of numerous feedstock chemicals with electron-deficient olefins. The active cuprate catalyst undergoes Ligand-to-Metal Charge Transfer (LMCT) to enable the generation of a chlorine radical which acts as a powerful hydrogen atom transfer reagent capable of abstracting strong electron-rich C(sp3)-H bonds.
S. M. Treacy, T. Rovis, J. Am. Chem. Soc., 2021, 143, 2729-2735.
N-heterocyclic carbenes catalyze intramolecular β-alkylations of α,β-unsaturated esters, amides, and nitriles that bear pendant leaving groups to form a variety of ring sizes. The mechanism is discussed.
C. Fischer, S. W. Smith, D. A. Powell, G. C. Fu, J. Am. Chem. Soc., 2006, 128, 1472-1473.
An intramolecular iodo-aldol cyclization of prochiral α-substituted enoate aldehydes and ketones produces hetero- and carbocycles containing quaternary centers adjacent to secondary or tertiary centers. The reactions occur in good yields and are highly trans-selective with hydroxyl and iodomethyl groups on opposite faces of the ring system.
F. Douelle, A. S. Capes, M. F. Greaney, Org. Lett., 2007, 9, 1931-1934.
The combination of Pd(PPh3)2Cl2 with Xantphos efficiently catalyzes a decarboxylative Heck reaction of vinyl arenes and vinyl heteroarenes with aliphatic N-(acyloxy)phthalimides under irradiation of blue LEDs at room temperature. A broad scope of secondary, tertiary, and quaternary carboxylates, including α-amino acid derived esters, can be converted with high stereoselectivity.
G.-Z. Wang, R. Shang, Y. Fu, Org. Lett., 2018, 20, 888-891.