Asymmetric Catalytic Alkynylation of Acetaldehyde: Application to the Synthesis of (+)-Tetrahydropyrenophorol

摘要

Enantiopure propargylic alcohols are highly potent functionalities present in a wide range of natural products or in pivotal synthetic building blocks. This is especially true for the propargylic alcohols where the substituent is a methyl (Scheme 1). Because of the ability to effect the chemo- selective elaboration of the alkyne unit, this process is potentially applicable to the innumerous targets bearing a chiral methyl carbinol subunit. Methods allowing access to these particularly attractive targets are relatively atom and time consuming. They are often based upon alkynylation via the lithiated alkyne and subsequent kinetic resolution or asymmetric reduction (Scheme 1).In addition, the use of the lithiated alkyne suffers from substrate compatibility. Alternatively, direct catalytic asymmetric alkynylation of aldehydes has recently appeared as a direct method of choice to access propargylic alcohols.