An Efficient, Stereoselective Approach to syn-1,2-Diols Protected as Cyclic Carbonates
摘要:
Enantioenriched 4-hydroxyalk-2-ynyl carbonates (or benzoates) have been prepared by stereoselective zinc-mediated addition of alkyl 2-propynyl carbonates (or their benzoate analogues) to aldehydes. Their partial reduction to Z-olefins followed by cyclization under mild Pd-catalyzed conditions allowed a straightforward access to enantioenriched syn-1,2-diols protected as cyclic carbonates.
Platinum complexes bearing phosphinous acids have efficiently promoted a tandem intermolecular sequence of [2+1]/[3+2] cycloaddition reactions. This process gave access to novel tricyclic systems and the cascade reactions were regio‐ and diastereoselective (see scheme; Cy=cyclohexyl). The [3+2] cycloaddition reaction was investigated further and two different alkyne partners were used.
Carbon Dioxide Utilisation for the Synthesis of Unsymmetrical Dialkyl and Cyclic Carbonates Promoted by Basic Ionic Liquids
作者:Peter Goodrich、H. Q. Nimal Gunaratne、Lili Jin、Yuntao Lei、Kenneth R. Seddon
DOI:10.1071/ch17530
日期:——
basic ionicliquids, via carbondioxide conversion, is described here. These ionicliquids were found to be effective bases for the fixation of carbondioxide by various alcohols and benzyl bromide, at room temperature. When the alcohol and the halide functionalities are present within the same substrate, the reaction cleanly produces a cyclic carbonate. These functionalised basic ionicliquids were
An efficient approach to alk-4-yne-l,2,3,6-tetraols is described by stereoselective addition of terminal 2-alkyn-1-yl esters to Ley's butane-2,3-diacetal-protected glyceraldehyde. The application of this methodology to a convenient synthesis of (-)-polyoxamic acid derivative is disclosed herein.
Palladium catalyzed hydrostannation of alkynes and palladium-catalyzed hydrostannolysis of propargyl or propargyloxycarbonyl derivatives of various functional groups