A simple method for the synthesis of 1,3-dioxolanes from carbonyl compounds has been developed using 1,2-bis(trimethylsilyloxy)ethane in the presence of bismuth(III) triflate as a catalyst. The bismuth(III) triflate catalyzed synthesis of a range of dioxanes and dioxepines has also been developed. In these latter cases, the carbonyl compound is treated with a diol, and triethyl orthoformate is used as a water scavenger. All these methods avoid the use of a Dean-Stark trap.
Chemoselective and Chemospecific Protection and Deprotection of a Carbonyl Group Using Polystyrene Divinylbenzene Sulfonic Acid
作者:Sanjeev K. Verma、Manisha Sathe、M. P. Kaushik
DOI:10.1080/00397910903161702
日期:2010.5.11
Chemospecific protection of one carbonylgroup of two identical carbonyls of 2,2-dialkyl-1,3-cyclohexanedione and chemoselective protection of aliphatic or aromatic carbonyls in the presence of conjugated carbonyl compounds using cross-linked polystyrene divinyl benzene sulfonic acid (SPS) as a heterogeneous catalyst has been demonstrated.
3,3,9,9-Tetramethyl-1,5,7,11-tetraoxaspiro[5.5]undecane is introduced as a new, stable and chemoselective reagent for the protection of aldehydes and ketones under mild reaction condition in high yield.
Iron(III) tosylate-catalyzed deprotection of aromatic acetals in water
作者:Margaret E. Olson、James P. Carolan、Michael V. Chiodo、Phillip R. Lazzara、Ram S. Mohan
DOI:10.1016/j.tetlet.2010.05.112
日期:2010.7
The deprotection of aromatic as well as conjugated acetals and ketals in water is catalyzed by iron(III) tosylate (1.0–5.0 mol %). Iron(III) tosylate is an inexpensive and readily available catalyst. The use of water, the most environmentally benign solvent, makes this procedure especially attractive for acetaldeprotection.
The synthesis and the liquid crystalline properties of a new class of conjugatedderivatives that assembled four oligophenylenevinylene (OPV) moieties arising from a calix[4]arene core are described. Photophysicalinvestigations also revealed strong electronic coupling between the four OPV fragments of the calix[4]OPV derivative.