破砕法で発生させた活性固体表面を利用した有機合成

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Several solvent-free organic syntheses were examined using the ball milling methodology. When bismuth shots were crushed in the presence of aromatic nitro compounds under dry conditions, azoxy and/or azo compounds were obtained in high yield. The use of powdered bismuth in place of shots led to poor results, indicating the important role of a newborn metal surface in the reductive dimerization of nitroarenes. Similar reaction using lead shots gave azo compounds as the sole product. Other commercially available metal shots did not afford any positive results. Ball milling of bismuth shots in the presence of aryl iodide and cuprous iodide resulted in the formation of triarylbismuthine in low to moderate yield. When pulverized in situ, natural minerals such as calcite and fluorite were found to be a mild and efficient catalyst for the condensation of aldehydes and active methylene compounds. Thus, when these minerals were crushed in the presence of substituted benzaldehydes and dimethyl malonate, the aldol type product (1) was obtained in good yield. No Knoevenagel type product (3) was produced. Prolonged reaction led to the formation of a 1,2-addition product (2), but interestingly enough, compound 3 failed to react with dimethyl malonate under the conditions employed.
基礎有機化学会（基礎有機化学連合討論会）の論文