NHC-mediated enantioselective formal [4 + 2] cycloadditions of alkylarylketenes and β,γ-unsaturated α-ketocarboxylic esters and amides.
نویسندگان
چکیده
Chiral N-heterocyclic carbenes (NHCs) promote the asymmetric formal [4 + 2] cycloaddition of alkylarylketenes with β,γ-unsaturated α-ketocarboxylic esters and amides. Divergent diastereoselectivity is observed in this process, with γ-aryl-β,γ-unsaturated α-ketocarboxylic esters and amides giving preferentially syn-dihydropyranones (up to 68 : 32 dr syn : anti, up to 98% ee), while γ-alkyl-derivatives generate anti-dihydropyranones (up to 18 : 82 dr syn : anti, up to 75% ee).
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ورودعنوان ژورنال:
- Organic & biomolecular chemistry
دوره 11 19 شماره
صفحات -
تاریخ انتشار 2013