Stereoselective Synthesis of Homopropargylic Allylic Ethers

Significance

In view of the recent upsurge in the chemistry of alkynes and allenes, practical methods to prepare them in enantiopure form are valuable. A wide variety of densely functionalized homopropargylic ethers were prepared in high diastereoselectivity by a one-pot, three component reaction. The authors used chiral allenylsilanes 2 as nucleophiles to add to aldehydes with complete transfer of chirality. Both enantiomers of the propargylic alcohol were obtained via an enzymatic kinetic resolution on the racemate of 1 on >35 g scale. The key chiral allenylsilane 2 was generated by a stereoselective Johnson-Claisen rearrangement.