A Novel Methodology for the Synthesis of Cyclic Carbonates Based on the Palladium-Catalyzed Cascade Reaction of 4-Methoxycarbonyloxy-2-butyn-1-ols with Phenols, Involving a Novel Carbon Dioxide Elimination-Fixation Process
摘要:
A palladium-catalyzed CO2-recycling reaction has been developed. Reaction of 4-methoxycarbonyloxy-2-butyn-1-ols with phenols, carried out in the presence of a palladium catalyst, produces phenoxy-substituted cyclic carbonates by way of a pathway involving a CO2 elimination-fixation. A variety of propargylic alcohols and phenols participate in these reactions which yield cyclic carbonates with high efficiencies. Stereoselective construction of trans-cyclic carbonates is achieved by using nonsymmetric substrates. Highly enantioselective reactions occur when (S)-BINAP is used as a ligand. Reaction of 4-phenoxycarbonyloxy2-butyn-1-ol in the presence of the palladium catalyst yields the corresponding cyclic carbonates via a three-component decomposition-reconstruction process.
Iodine sets allenes ringing: A novel iodine‐promoted tandem cyclization reaction of but‐2‐yne‐1,4‐diol and 4‐aminobut‐2‐yn‐1‐ol derivatives leading to substituted 3,4‐diiodoheterocyclic compounds has been developed (see scheme). In this reaction, a trace amount of water is needed. Both the iodine anion and cation generated from I2 are used in the reaction. The resulting iodides can then be used in