: A mild reagent for the regioselective reductive ring opening of benzylidene acetals in carbohydrates
作者:Lu Jiang、Tak-Hang Chan
DOI:10.1016/s0040-4039(97)10599-8
日期:1998.1
is an effective reagent to reductively cleave 4,6-O-benzylidene acetals of various hexopyranosides to the corresponding 4-O-benzyl ethers. 4,6-O-Isopropylidene acetals can be similarly cleaved. Common protecting groups are stable to the reaction conditions.
1,1,3,3-Tetramethyldisiloxane (TMDS) has been developed as an excellent dual-purposereductant for the highly regioselectiveringcleavage of various hexopyranosyl 4,6-O-acetals with Cu(OTf)2 or AlCl3 to afford the corresponding primary and secondary ethers. Its application to the concise synthesis of carbohydrate-based surfactants is highlighted.
Iodine–sodium cyanoborohydride-mediated reductive ring opening of 4,6-O-benzylidene acetals of hexopyranosides
作者:Kaki Venkata Rao、Premanand R. Patil、Sridhar Atmakuri、K.P. Ravindranathan Kartha
DOI:10.1016/j.carres.2010.10.013
日期:2010.12
A quick, efficient and convenient method for the regiospecific reductiveringopening of 4,6-O-benzylidene acetals of O-/S-alkyl/aryl glycosides of mono- and disaccharides, leading to the exclusive formation of the corresponding 6-O-benzyl ethers, using sodium cyanoborohydride in the presence of molecular iodine, is reported. It has been observed that common protecting groups such as ethers and esters
SnCl4 Promoted Efficient Cleavage of Acetal/Ketal Groups with the Assistance of Water in CH2Cl2
作者:Tao Luo、Tian-Tian Xu、Yang-Fan Guo、Hai Dong
DOI:10.3390/molecules27238258
日期:——
carbohydrates containing acetal/ketal groups with the assistance of water in CH2Cl2 led to deacetalization/deketalization products in almost quantitative yields. In addition, for substrates containing both acetal/ketal and p-methoxylbenzyl groups, we also found that the p-methoxylbenzyl group was selectively cleaved by the use of a catalytic amount of SnCl4, while the acetal/ketal groups remained. Furthermore