Categories: C-S Bond Formation, Synthesis of S-Heterocycles >
Synthesis of thioacetals
Protecting Groups
1,3-Dithianes, 1,3-Dithiolanes
Recent Literature
Various carbonyl compounds including aliphatic and aromatic aldehydes and
ketones were converted to the corresponding thioacetals in high yields in the
presence of a catalytic amount of hafnium trifluoromethanesulfonate. The mild
conditions tolerated various sensitive functional and protecting groups and were
racemization-free when applied to R-aminoaldehydes.
Y.-C. Wu, J. Zhu, J. Org. Chem., 2008,
73, 9522-9524.
Tungstophosphoric acid (H3PW12O40) was
found to be an effective and highly selective catalyst for the
thioacetalization of aldehydes, ketones, acetals, acylals and O,S-acetals
in excellent yields in the absence of solvent. Chemoselective conversions of
α- or β-diketones and a β-keto ester are described. Sterically hindered
carbonyl compounds were converted to the corresponding thioacetals in
refluxing petroleum ether in good yields.
H. Firouzabadi, N. Iranpoor, K. Amani, Synthesis, 2002, 59-60.
Dihydrosulfenylation of alkynes with thiols can be achieved by using a zinc
catalyst to provide dithioacetals regioselectively in excellent yields. A
hydrosulfenylation of alkenes can also be performed.
N. Taniguchi, K. Kitayama, Synlett, 2018, 29,
2712-2716.
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.
A new procedure for the protection of aldehydes and
ketones as thioacetals promoted by catalytic amount of p-toluenesulfonic acid
and silica gel has been developed. This procedure offers versatility, short
reaction time, excellent yield, and is easy to carry out. A simple filtration
followed by removal of solvent in most cases produces pure product.
M. H. Ali, M. G. Gomes, Synthesis, 2005, 1326-1332.
M. H. Ali, M. G. Gomes, Synthesis, 2005, 1326-1332.
Aldehydes and ketones were protected as their thioacetals in the presence of
a catalytic amount of iodine. These mild reaction conditions were also applied
in the transthioacetalization of O,O-acetals, O,O-ketals,
O,S-acetals, and acylals.
H. Firouzabadi, N. Iranpoor, H. Hazarkhani, J. Org. Chem., 2001, 66, 7527-7529.