Highly enantioselective gold-catalyzed intramolecular cyclization of N-allenamides was implemented by utilizing a designed chiral sulfinamide phosphine ligand (PC-Phos). This represents the first example of highly enantioselective intramolecular cyclization of N-allenamides. The practicality of this reaction was validated in the total synthesis of (R)-desbromoarborescidine A and formal synthesis of (R)-desbromoarborescidine C and (R)-deplancheine. Moreover, the catalyst system PC-Phos/AuNTf proved to be specifically efficient to promote the desymmetrization of N-allenamides in excellent yields with satisfactory ee values.
The highly exo-and enantioselective goldcatalyzed tandem heterocyclization/[4 + 3] cycloaddition of 2-(1-alkynyl)-2-alken-1-ones and 1,3-diphenylisobenzofuran was implemented by utilizing Ming-Phos, which provides a facile access to chiral seven-membered oxa-bridged rings in 80−98% yield with high exo selectivity (exo/endo up to 50:1) and up to 97% ee.
A gold(I)‐catalyzed highly diastereo‐ and enantioselective intermolecular cycloaddition of oxime ethers with nitrones under mild conditions was developed, which provides an facile access to optically pure highly substituted pyrrolo[3,4‐d][1,2]oxazines. The salient features of this reaction include general substrate scope, high efficiency, high enantioselectivity, readily available starting materials, and the use of commercially available ligand.
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