金属ストロンチウムを用いるＢａｒｂｉｅｒ型アルキル化反応の開発

Abstract

Organometallic compounds comprise some of the most versatile reagents in organic synthesis, and among them are organometallic compounds of alkaline-earth elements. Numerous reports have been published on the Grignard (or Barbier) reaction using metallic magnesium and alkyl halides. Furthermore, there are various reports on the preparation and reactivity of the organometallic compounds of calcium and barium. In contrast, fewer studies on the preparation and reactivity of organostrontium compounds were found in the literature. As the results on our investigation, it's found that in the presence of metallic strontium, the Barbier-type alkylation of aldehydes with alkyl iodides proceeded smoothly at-15°C under an argon atmosphere to afford the corresponding alkylated alcohols in moderate to good yields. The Barbier-type alkylation of imines with alkyl iodides also took place smoothly at room temperature under an argon atmosphere to give the corresponding alkylated amines in good yields. Aromatic aldimines reacted with metallic strontium in the presence of a catalytic amount of iodine to obtain the self-coupling products in good yields. Furthermore, the Barbier-type alkylation of esters with alkyl iodides proceeded smoothly at room temperature under an argon atmosphere to afford the corresponding dialkylated alcohols in good yields.