科研之友
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摘要
(Z) Enol triflates 6, 11b-d, (E) enol. triflate 11e, and phenol triflate 11a, derived from beta-keto esters or 2-carboalkoxy phenols, respectively, react with N-Boc 2-lithiopyrrolidine (5a), N-Boc N-methylaminomethyllithium (5b), or 2-lithio-1,3-dithiane (14) to afford 3(2H)-furanones in-modest to good yields (38-81%). Product and carbanion reagent studies suggest that the 3(2H)-furanone is formed in a cascade of reactions involving nucleophilic acyl substitution, enolate formation; trifluoromethyl transfer, iminium or sulfenium ion formation, and subsequent ring closure to form the 3(2H)-furanone. The use of 2-lithio-1,3-dithiane affords a cyclic alpha-keto-S,S,O-orthoester in which the functionality can be selectively manipulated for synthetic applications.
- 出版日期2016-2-19
