Synthesis of oxathioacetals
Treatment of symmetrical O,O-acetals with TESOTf and 2,4,6-collidine formed weakly electrophilic collidinium salts. Subsequent addition of nucleophiles, such as alcohols, lithium thioxide, and sodium azide, to the salts afforded the corresponding O,O-mixed, O,S- and N,O-acetals in good yields.
H. Fujioka, T. Okitsu, T. Ohnaka, R. Li, O. Kubo, K. Okamoto, Y. Sawama, Y. Kita, J. Org. Chem., 2007, 72, 7898-7902.
A Pd-catalyzed addition of thiols to alkenes bearing a heteroatom, such as oxygen and nitrogen, proceeds under mild conditions to give regioselectively the corresponding Markovnikov adducts in good yields.
T. Tamai, A. Ogawa, J. Org. Chem., 2014, 79, 5028-5035.
Various carbonyl compounds can be easily and rapidly converted to the corresponding 1,3-oxathiolanes in the presence of a catalytic amount of scandium(III) triflate in CH2Cl2. The catalyst can be recovered. A chemoselective oxathioacetalization of aldehydes in the presence of ketones can be achieved.
B. Karimi, L. Ma'mani, Synthesis, 2003, 2503-2506.
A simple and convenient synthetic protocol for the protection of hydroxyl groups as tetrahydropyranyl ethers as well as carbonyl functionalities as oxathioacetals and thioacetals has been achieved using a catalytic amount of silica-supported perchloric acid under solvent-free conditions.
A. T. Khan, T. Parvin, L. H. Choudhury, Synthesis, 2006, 2497-2502.
Carbonyl compounds have been successfully converted into their corresponding oxathiolane, dithiolane, and dithiane derivatives with 2-mercaptoethanol, 1,2-ethanedithiol, and 1,3-propanedithiol using a catalytic amount of yttrium triflate. In addition, by using this catalyst, highly chemoselective protection of aldehydes has been achieved.
S. K. De, Tetrahedron Lett., 2004, 45, 2339-3241.