Synthesis of Polyfunctional Allenes by Successive Copper-Mediated Substitutions

Chem. Eur. J., 2011, 17, 4232-4237 published on 07.03.2011
Readily available 1,1-dichloro- 2-alkynes are versatile starting materials for the synthesis of polyfunctionalized allenes. They can be prepared from commercially available terminal alkynes in a two-step procedure. The Cu-mediated reaction of several 1,1-propargylic derivatives with functionalized alkyl, benzylic, or allylic zinc reagents proceeds exclusively with SN2’ selectivity and allows a rapid and efficient synthesis of functionalized chloro- ACHTUNGTRENUNGallenes. These chloroallenes undergo a novel CuI-catalyzed substitution reaction with functionalized arylmagnesium reagents with excellent SN2 selectivity to give trisubstituted polyfunctionalized allenes. The functional group tolerance is excellent and functionalities, such as cyano, keto, ester, phosphate, trifluoromethyl, and halogens, are well tolerated
TU München