2,4,4,6-Tetrabromo-2,5-cyclohexadienone (TABCO), N-Bromosuccinimide (NBS) and Bromine as Efficient Catalysts for Dithioacetalization and Oxathioacetalization of Carbonyl Compounds and Transdithioacetalization Reactions
作者:Nasser Iranpoor、Habib Firouzabadi、Hamid Reza Shaterian、M. A. Zolfigol
DOI:10.1080/10426500211712
日期:2002.5.1
6-tetrabromo-2,5-cyclohexadienone (TABCO), N-bromosuccinimide (NBS), and bromine as efficient catalysts for conversion of carbonyl compounds to their cyclic and acyclic dithioacetals and 1,3-oxathiolanes under mild reaction conditions are described. These catalysts are also used for efficient transdithioacetalization of acetals, diacetals, ketals, acylals, enamines, hydrazones, and oximes with high
Unusually facile oxathioacetal transfer reaction: an efficient, highly selective catalytic deprotection protocol
作者:T. Ravindranathan、Subhash P. Chavan、Jos P. Varghese、Shubhada W. Dantale、Rajkumar B. Tejwani
DOI:10.1039/c39940001937
日期:——
CF3SO3SiMe3-catalysed one-to-one exchange of oxathioacetals to carbonyl compounds in the presence of 4-nitrobenzaldehyde is performed efficiently at room temperature, the protocol developed provided selective and effective deprotection of oxathiolanes in the presence of thioacetals.
An exceptionally simple and catalytic method for regeneration of carbonyl functionality from the corresponding 1,3-oxathiolanes
作者:Ejabul Mondal、Priti Rani Sahu、Gopal Bose、Abu T. Khan
DOI:10.1039/b110305a
日期:2002.4.9
A wide variety of 1,3-oxathiolanes 1 can be chemoselectively deprotected to the corresponding carbonyl compounds 2 in good yields by employing V2O5–H2O2 catalyzed oxidation of ammonium bromide in a CH2Cl2–H2O mixture at 0–5 °C. Some of the major advantages of this procedure are its mild conditions, and that it is highly selective and efficient, high yielding, and cost-effective. Furthermore, no brominations occur at the double bond or allylic position or α to the keto position or aromatic ring.
A Useful and Catalytic Method for Protection of Carbonyl Compounds into the Corresponding 1,3-Oxathiolanes and Deprotection to the Parent Carbonyl Compounds
作者:Ejabul Mondal、Priti Rani Sahu、Abu T. Khan
DOI:10.1055/s-2002-20466
日期:——
A wide variety of carbonyl compounds 1 can be easily protected to the corresponding 1,3-oxathiolanes 2 in good yields in the presence of catalytic amount of perchloric acid in dry CH2Cl2 at 0-5 °C. On the other hand, various 1,3-oxathiolanes 2 can be selectively deprotected to the parent carbonyl compounds 1 in very good yields by H2MoO4·H2O-H2O2 catalyzed oxidation of ammonium bromide in the presence of perchloric acid in CH2Cl2-H2O solvent system. Mild reaction condition, high selectivity, efficient and relatively good yields are some of the major advantages of the procedure.