Enantioselective Syntheses of Homopropargylic Alcohols via Asymmetric Allenylboration
摘要:
A chiral phosphoric acid catalyzed allenylboration reaction is reported. Homopropargyl alcohols with an internal alkyne unit were obtained in good yields with high enantioselectivities under the developed conditions.
Copper(I)-Catalyzed Substitution of Propargylic Carbonates with Diboron: Selective Synthesis of Multisubstituted Allenylboronates
摘要:
A versatile synthetic method for the preparation of the allenylboronates, Cu(I)-catalyzed reaction of propargylic carbonates with a diboron, is described. A Cu(O-t-Bu)-Xantphos catalyst system was effective for the preparation of various allenylboron compounds, allenylboronates with different substitution patterns, those with functional groups, and an axially chiral one. The Lewis acid promoted stereoselective addition to aldehydes leading to homopropargylic alcohols showed the usefulness of the new allenylboronates.