Synthesis of Baylis-Hillman adducts (α,β-unsaturated compounds)
The samarium diiodide promoted addition of α-halo-α,β-unsaturated esters to carbonyl compounds led to (Z)-2-(1-hydroxyalkyl)-2,3-alkenoates in good yields and very high stereoselectivity. A mechanism is proposed to explain this transformation.
J. M. Concellon, M. Huerta, J. Org. Chem., 2005, 70, 4714-4719.
Silica gel-DABCO catalyzed oxidation of alcohols to aldehydes with chloramine-T followed by their Morita-Baylis-Hillman reaction with acrylonitrile or methyl acrylate gives good overall yields of the corresponding Morita-Baylis-Hillman adducts. The present work opens up a new and efficient synthetic route to Morita-Baylis-Hillman adducts directly from alcohols in a one-pot operation.
L. D. S. Yadav, V. P. Srivasta, R. Patel, Synlett, 2010, 1047-1050.
Various ketones as the electrophiles react in a one pot three-component coupling with an aluminum allenoate intermediate derived from ethyl propiolate and alluminium iodide to yield β-iodo Morita-Baylis-Hillman adducts with high yield and excellent Z-stereoselectivity.
S. Il Lee, G.-S. Hwang, D. H. Ryu, Synlett, 2007, 59-62.
A nickel(0)-catalyzed coupling of α-olefins and isocyanates in the presence of an N-heterocyclic carbene ligand proceeds preferentially at the 2-position of the olefin to provide α,β-unsaturated amides. N-tert-butyl amide products can be converted to the corresponding primary amides under acidic conditions.
K. D. Schleicher, T. F. Jamison, Org. Lett., 2007, 9, 875-878.
A dynamic kinetic asymmetric transformation (DYKAT) process constitutes a reasonable alternative strategy to access versatile Baylis-Hillman derivatives in highly enantiomerically enriched form. By using an oxygen nucleophile that can become a hydroxyl group, the process constitutes a deracemization.
B. M. Trost, H.-C. Tsui, F. D. Toste, J. Am. Chem. Soc., 2000, 122, 3534-3535.