Mechanistic Studies on the Base-Promoted Conversion of Alkoxy-Substituted, Ring-Fused gem-Dihalocyclopropanes into Furans: Evidence for a Process Involving Electrocyclic Ring Closure of a Carbonyl Ylide Intermediate

作者：Sharp Phillip P; Mikusek Jiri; Ho Junming; Krenske Elizabeth H; Banwell Martin G^*; Coote Michelle L; Ward Jas S; Willis Anthony C

来源：Journal of Organic Chemistry, 2018, 83(22): 13678-13690.

DOI：10.1021/acs.joc.8b01766

The mechanism associated with the base-promoted conversion of alkoxy-substituted and ring-fused gem-dihalocyclopropanes such as 40 into annulated furans has been explored. Treatment of compound 40 with potassium tert-butoxide affords a mixture of furans 23/27 and 41, an outcome that suggests the intermediacy of the slowly inter converting carbonyl ylides 42 and 43 that undergo rapid [1,5]-electrocyclizations and subsequent dehydrohalogenation to afford the observed products. This proposal is supported by ab initio MO and DFT calculations that also suggest a vinyl-carbene insertion pathway is less likely to be operative.

• 出版日期2018-11-16