Synthesis of cyclohexanes
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.