Cobalt-Catalyzed Regio- and Diastereoselective Formal [3 + 2] Cycloaddition between Cyclopropanols and Allenes

A cobalt–diphosphine
catalyst has been found to promote
a formal [3 + 2] cycloaddition reaction between a cyclopropanol and
an allene via cyclopropanol ring opening, which affords a 3-alkylidenecyclopentanol
derivative with high regio- and diastereoselectivities. The reaction
tolerates monosubstituted, 1,1-disubstituted, and 1,3-disubstituted
allenes and various functional groups. The reaction is proposed to
proceed through carbometalation of the allene with a cobalt homoenolate
followed by intramolecular carbonyl allylation of the resulting allylcobalt
species.

研究发现，钴-二膦催化剂可通过环丙醇开环路径，催化环丙醇与丙二烯发生形式上的[3+2]环加成反应，以优异的区域选择性与非对映选择性生成3-亚烷基环戊醇衍生物。该反应具有良好的底物兼容性，可适配单取代、1,1-二取代及1,3-二取代丙二烯与多种官能团。据推测，该反应的反应历程为：钴高烯醇盐对丙二烯进行碳金属化，随后使生成的烯丙基钴物种发生分子内羰基烯丙基化。