Perfluorophenylboronic acid-catalyzed direct α-stereoselective synthesis of 2-deoxygalactosides from deactivated peracetylated <scp>d</scp>-galactal
作者:Madhu Babu Tatina、Ziad Moussa、Mengxin Xia、Zaher M. A. Judeh
DOI:10.1039/c9cc06151g
日期:——
Perfluorophenylboronic acid 1c catalyzes the direct stereoselective addition of alcohol nucleophiles to deactivated peracetylated d-galactal to give 2-deoxygalactosides in 55-88% yield with complete α-selectivity. The unprecedented results reported here also enable the synthesis of disaccharides containing the 2-deoxygalactose moiety directly from the deactivated peracetylated d-galactal. This convenient and metal-free
The chain elongation of primaryalcohol of saccharides (α-d-ribose, α-d-glucose, α-d-mannose) and a disaccharide (α-d-melibiose) has been achieved via a Mitsunobureactionusing bis(2,2,2-trifluoroethyl) malonate as nucleophile.
Synthesis of Unsymmetrical Difluoromethylene Bisphosphonates
作者:Jianyun Guo、Pascal Balić、Vladimir S. Borodkin、Dmitri V. Filippov、Jeroen D. C. Codée
DOI:10.1021/acs.orglett.3c04211
日期:2024.1.26
We demonstrate the use of the symmetrical diethyl(dimethyl)difluoromethylene bisphosphonate reagent for the synthesis of terminal and unsymmetrical difluoromethylene bisphosphonates, close analogues of biologically important molecules. The difference in reactivity of the methyl and ethyl groups in the symmetrical diethyl(dimthyl)difluoromethylene bisphosphonate is exploited in a stepwise demethylation–condensation
Regio- and Chemoselective Deprotection of Primary Acetates by Zirconium Hydrides
作者:Marine Gavel、Thibaut Courant、Antoine Yvan Philippe Joosten、Thomas Lecourt
DOI:10.1021/acs.orglett.8b03947
日期:2019.4.5
A combination of DIBAL-H and Cp2ZrCl2 is shown to promote the regioselective cleavage of primary acetates on a broad scope of substrates, ranging from carbohydrates to terpene derivatives, with a high tolerance toward protecting groups and numerous functionalities found in natural products and bioactive compounds. Apart from providing highly valuable building blocks in only two steps from biosourced raw materials, this selective de-O-acetylation should also be strongly helpful to solve selectivity issues in organic synthesis.
Enzymes in carbohydrate synthesis. Lipase-catalyzed selective acylation and deacylation of furanose and pyranose derivatives
作者:William J. Hennen、H. Marcel Sweers、Yi Fong Wang、Chi Huey Wong