Development of neighboring electrophilic activation of active center in catalytic reactions via organometallic intermediates

Abstract

Strategies for electrophilic activation by neighboring atoms should contribute to the development of novel catalytic performance in organic reactions. Neighboring electron-withdrawing Lewis acidic atoms can change the character of molecular catalysts, which might be more electrophilic toward inactive electron-rich molecules. In this context, the development of carbene intermediates, diborylmethane derivatives, and multinuclear catalysts has realized efficient transformations. The use of cyclopropenes can generate electrophilic carbenoid intermediates in the presence of a Ag-catalyst, the reaction of which with an organozinc reagent gives allylzinc intermediates. The subsequent allylation reaction of other electrophiles takes place in situ as a 3-components coupling reaction. The novel reactivity of diborylmethane derivatives shows the generation of borate intermediates under ambient conditions, which can take part in the SuzukiMiyaura cross-coupling reaction. The mono-coupling reaction occurs exclusively without di-coupling reaction to give alkylboronates. The stereoselective synthesis of tetrasubstituted alkenylboronates was successful via the deprotonation of diborylalkanes, subsequent nucleophilic attack to ketones, and syn-elimination. The development of multinuclear catalysts using phosphorous ligands bearing protic moieties has realized efficient stereoselective 1,4-addition reaction of organozinc and organoaluminum reagents, where the creation of chiral quaternary stereogenic centers using acyclic enones is notable.