1370340-56-9Relevant academic research and scientific papers
Enantioselective synthesis of allenes by catalytic traceless petasis reactions
Jiang, Yao,Diagne, Abdallah B.,Thomson, Regan J.,Schaus, Scott E.
, p. 1998 - 2005 (2017/02/15)
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.
A direct synthesis of allenes by a traceless petasis reaction
Mundal, Devon A.,Lutz, Kelly E.,Thomson, Regan J.
, p. 5782 - 5785 (2012/05/07)
A one-pot synthesis of allenes by the 2-nitrobenzenesulfonylhydrazide- mediated coupling of hydroxyaldehydes or ketones with alkynyl trifluoroborate salts is reported. This mild process involves in situ formation of a sulfonylhydrazone that reacts with alkynyl trifluoroborates to generate a transient propargylic hydrazide species. Decomposition of this unstable hydrazide via an intermediate monoalkyldiazine produces the allene products through an alkene walk mechanism.
