10.1021/jacs.6b11937.s001 Yao Jiang Yao Jiang Abdallah B. Diagne Abdallah B. Diagne Regan J. Thomson Regan J. Thomson Scott E. Schaus Scott E. Schaus Enantioselective Synthesis of Allenes by Catalytic Traceless Petasis Reactions American Chemical Society 2017 nucleophilic addition traceless Petasis reaction allyl boronates alkynyl imines enantioenriched chiral allenes sulfinic acid propargylic diazene chemical properties allenes chiral chiral allenes glycolaldehyde imine reactivity patterns enantioselective methods enantioselective approaches Catalytic Traceless Petasis Reactions Allenes chiral biphenols alkynyl boronates Mannich product achiral precursors access enantioenriched allenes allylic hydroxyl allenes sulfonyl hydrazones boronate addition Enantioselective Synthesis 2017-01-25 14:18:45 Journal contribution https://acs.figshare.com/articles/journal_contribution/Enantioselective_Synthesis_of_Allenes_by_Catalytic_Traceless_Petasis_Reactions/4585195 Allenes are useful functional groups in synthesis as a result of their inherent chemical properties and established reactivity patterns. One property of chemical bonding renders 1,3-substituted allenes chiral, making them attractive targets for asymmetric synthesis. While there are many enantioselective methods to synthesize chiral allenes from chiral starting materials, fewer methods exist to directly synthesize enantioenriched chiral allenes from achiral precursors. We report here an asymmetric boronate addition to sulfonyl hydrazones catalyzed by chiral biphenols to access enantioenriched allenes in a traceless Petasis reaction. The resulting Mannich product from nucleophilic addition eliminates sulfinic acid, yielding a propargylic diazene that performs an alkyne walk to afford the allene. Two enantioselective approaches have been developed; alkynyl boronates add to glycolaldehyde imine to afford allylic hydroxyl allenes, and allyl boronates add to alkynyl imines to form 1,3-alkenyl allenes. In both cases, the products are obtained in high yields and enantioselectivities.