Categories: C-S Bond Formation >
Synthesis of β-sulfido carbonyl compounds and related compounds
Recent Literature
β-Sulfido carbonyl compounds were formed at room temperature, in short times
and with excellent chemoselectivity by a catalyst-free conjugate addition of
thiols to ,-unsaturated carbonyl compounds in water. Competitive dithiane/dithiolane
formation, transesterification, and ester cleavage were not observed.
G. L. Khatik, R. Kumar, A. K. Chakraborti, Org. Lett.,
2006, 8, 2433-2436.
Tetrabutylammonium bromide is an inexpensive ionic liquid, which efficiently catalyzes the conjugate addition of thiols to α,β-unsaturated
nitriles, carboxylic esters, ketones and aldehydes as well as nitro olefins.
B. C. Ranu, S. S. Dey, A. Hajra, Tetrahedron, 2003, 59,
2325-2331.
A rapid conjugate addition of thiols to α,β-unsaturated ketones is achieved
in a hydrophobic ionic liquid [bmim]PF6/H2O solvent system in the absence of any acid catalyst. This mild and neutral method gave the
corresponding Michael adducts in high yields with excellent
1,4-selectivity. The ionic liquid can be reused.
J. S. Yadav, B. V. S. Reddy, G. Baishya, J. Org. Chem., 2003, 68, 7098-7100.
A versatile RuCl3-catalyzed 1,4-conjugate addition of primary,
secondary and aromatic amines, thiols, and carbamates to α,β-unsaturated
compounds in poly(ethylene glycol) (PEG) provides the desired β-substituted
carbonyls in high yields. RuCl3-PEG offers low sensitivity toward moisture and
oxygen, high tolerance of different functional groups, and efficient
recyclability.
H. Zhang, Y. Zhang, L. Liu, H. Xu, Y. Wang, Synthesis, 2005,
2129-2136.
S-Alkylisothiouronium salts are a nontoxic, odorless and simply
operational alternative of thiols for the thia-Michael addition with
electron-deficient olefins. The reactions were carried out under alkaline
conditions in water at room temperature within short reaction times to afford
the expected products in good yields.
Y. Zhao, Z.-M. Ge, T.-M. Cheng, R.-T. Li, Synlett, 2007,
1529-1532.
CeCl3 • 7H2O/NaI supported on
neutral alumina (Al2O3) promotes heteroatom Michael
additions under solvent-free conditions. The CeCl3 • 7H2O/NaI/Al2O3
system works well for hetero-Michael additions of weak nucleophiles such as
imidazoles and carbamates to various acceptors.
G. Bartoli, M. Bartolacci, A. Giuliani, E. Marcantoni, M. Massaccesi, E.
Torregiani, J. Org. Chem., 2005,
70, 169-174.
β-Keto 1,3-dithianes can be generated by the double conjugate addition of
dithiols to propargylic ketones, esters and aldehydes in excellent yields.
These masked 1,3-dicarbonyl systems can be converted to a range of
functionalised oxygen-containing heterocycles that can be used in natural
product synthesis.
M. J. Gaunt, H. F. Sneddon, P. R. Hewitt, P. Orsini, D. F. Hook, S. V. Ley,
Org. Biomol. Chem., 2003, 1, 15-16.
