The Grubbs first-generation catalyst has been found to be an effective catalyst for the synthesis of enaminones by coupling thioamides with α-diazodicarbonyl compounds. The reaction is successful in converting primary, secondary, and tertiary thioamides into their corresponding enaminones. The reaction is also suitable for the synthesis of chiral enaminones.
Enaminones can be prepared via the Rh2(OAc)4-catalyzed coupling of α-diazocarbonyl compounds with thioamides. However, rhodium is the most expensive and least abundant among the dominant precious metals used for catalysis. Furthermore, a very limited substrate scope is known for the intermolecular rhodium catalyzed coupling reaction. Therefore, there is a need to find a more economical catalyst substitute with a broad substrate scope. In this paper, we describe the use of Ru(II) catalysts for the synthesis of enaminones. The reaction can be performed efficiently with the Grubbs first-generation catalyst or [(Ph)3P]3RuCl2 in a sealed tube. Both catalysts are much less expensive than Rh2(OAc)4. Secondary and tertiary thioamides, when reacted with α-diazodiesters, α-diazoketoesters, α-diazodiketones, and α-diazomonoketones give enaminones. Primary thioamides give thiazole derivatives when reacted with α-diazomonoketones. However, with other diazo compounds, primary thioamides also give enaminones. All enaminones are obtained in good yields and with good diastereoselectivity. Accordingly, the method described in this paper is an efficient and economical alternative to the Rh2(OAc)4-catalyzed coupling process.
Enaminones are commonly prepared by the Eschenmoser coupling reaction. The duration of the reaction is often long. Here, we describe how sonication can accelerate this reaction. The reaction conditions provide an efficient method for the coupling of primary, secondary and tertiary thioamides with a-bromocarbonyl compounds.
Research suggests that one's perceptions of an ideal leader do not always match one's perceptions of an ideal woman. The roles are incongruous. This study used a causal-comparative methodology to examine role congruity theory within Protestant evangelical nonprofit organizations in order to discover whether or not role incongruity posed as an obstacle for women leaders. Participants completed one of the seven versions of the revised Descriptive Index, in addition to providing basic demographic information. Similar to previous research, results indicated that role congruity emerged as an obstacle for women. Unlike previous research, role congruity emerged as an issue for men as well. Furthermore, male managers differed more from successful middle managers than did female managers.
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