Cerium triflate: An efficient and recyclable catalyst for chemoselective thioacetalization of carbonyl compounds under solvent-free conditions
A simple and efficient chemoselective thioacetalization of carbonyl compounds has been achieved using Ce(OTf)3 (10 mol-%) as a catalyst under solvent-free conditions. Advantages of the methodology include very short reaction times, excellent yi
Kumar, Anil,Rao, M. Sudershan,Kameshwara Rao
experimental part
p. 135 - 140
(2010/05/18)
Chemoselective dithioacetalisation of carbonyl compounds under solvent-free conditions
Dithioacetalisation of carbonyl compounds in the presence of other structurally different aldehydes and ketones was achieved chemoselectively in the presence of Cdl2 under microwave irradiation in solvent free conditions.
Laskar,Prajapati,Sandhu
p. 313 - 315
(2007/10/03)
Lithium bromide-catalyzed highly chemoselective and efficient dithioacetalization of α,β-unsaturated and aromatic aldehydes under solvent-free conditions
Chemoselective dithioacetalization of aromatic- and α,β- unsaturated aldehydes in the presence of other structurally different aldehydes and ketones was achieved efficiently in the presence of catalytic amounts of LiBr under solvent-free conditions. Due to the neutral reaction conditions, this method is compatible with acid sensitive substrates.
Firouzabadi, Habib,Iranpoor, Nasser,Karimi, Babak
p. 58 - 60
(2007/10/03)
Chemoselective Protection of Aldehydes as Dithioacetals in Lithium Perchlorate-Diethyl Ether Medium. Evidence for the Formation of Oxocarbenium Ion Intermediate from Acetals
Aldehydes and acetals were very efficiently converted to acyclic and cyclic dithioacetals in 5 M lithium perchlorate/diethyl ether (LPDE) medium at ambient temperature in high yields.Spectroscopic and other experimental evidences strongly suggest the formation of oxocarbenium ion intermediates from acetals in 5 M LPDE which subsequently reacted with thiols to give the dithioacetals.Under the same conditions ketones and their acetals also reacted, albeit very slowly compared to aldehydes and acetals, to yield dithioacetals.The difference in their reactivity was successfully employed in the chemoselective dithioacetalization of aldehydes and acetals in the presence of ketones and their acetals.The chemoselective dithioacetalization of keto aldehydes has been realized with the keto group remaining intact.The present method offers a convenient, efficient, and neutral medium for the deprotection of acetals to aldehydes and also the chemoselective protection of aldehydes to dithioacetals.
Saraswathy, V. Geetha,Sankararaman, S.
p. 4665 - 4670
(2007/10/02)
Pyrylium Salt Sensitized Photochemical Deprotections of Dithioacetals and Ketals
Photoreactions of various dithioacetals and ketals using tris(p-chlorophenyl)pyrylium perchlorate as a sensitizer were studied.Irradiation (λ>360 nm) of dichloromethane solutions containing dithioacetals or ketals and pyrylium salt afforded the corresponding carbonyl compounds in good to excellent yields in the presence of molecular oxygen.