Synthesis of Chiral Allenyl Synthesis of Chiral Allenyl Ethers: Memory of Chirality in the Cyclization Reactions of Oxyallyl in the Cyclization Reactions of Oxyallyl Cations Potential Reaction Pathways f or Asymmetric Reactions of Oxyallyl Cations with 'Memory of Chirality' R3 2
R
OR O
R3
OR R1
R1 2
R
O
3 H R O
OR
H 1
H Nu OR R2
O
R1
enantiomerically enriched products
OR
R3 R2
O
H
R2
R
chiral conf ormation; Is cyclization f aster than bond rotation?
E enantiomerically enriched products
enantiomerically enriched products
• Reactive oxyallyl cations generated from readily prepared allenyl carbamates • Simple oxidation with DMDO initiated a highly diastereoselective cycloaddition reaction providing the desired tricyclic product as a single diastereoisomer • With ready access to enantiomerically pure allenyl carbamates, the evaluation of memory of chirality in this process is currently underway
Corey R. J. Stephenson, Boston University
