Development of Synthetic Organic Reactions Based on New Manganese Chemistry

发现锰（II）盐加速4-戊烷酸锂的环化生成阴离子环化中间体，中间体与三氟乙酸酐进一步反应生成酰基化的α-亚甲基四氢呋喃和二氢呋喃混合物。可选择性地选择碱金属的醇氧化物和反应条件，得到各种产物。除三氟乙酸酐外，苯甲酰溴和乙二烯丙酸酯也可与中间体反应。该反应既能实现环化，又能在一个釜中引入环化中间体的碳侧链。在较低温度下，有机锰酸盐与路易斯酸不发生反应，这种有机锰酸盐与路易斯酸的混合物将缩醛转化为相应的取代产物。Ketal也与“混合试剂”发生反应。还发现烷基锂试剂在铁催化剂存在下与共轭炔反应生成烷基化共轭炔。烷基镁试剂也提供烷基化炔。有趣的是，在烷基锂的反应中，加成反应以顺式加成的方式进行，而相应的加合物——乙烯基锂在平衡状态下异构为顺式-反式混合物。当乙醚官能团在双炔底物中时，只得到反式加合物，表明平衡完全转向反式加合物。有趣的是，格氏试剂即使在含醚部分的双炔反应中也只能产生顺式加合物。这些乙烯基锂和镁的中间体非常活泼，甚至与DMF和氧化烷反应。

It was found that manganese(II) salt accelerated cyclization of lithium 4-pentynyl alkoxides to give anionic cyclized intermediates, which reacted further with trifluoroacetic anhydride to afford acylated α-methylenetetrahydrofurans and dihydrofurans as a mixture. Each product could be obtained selectively choosing alkaline metal of alkoxide and reaction conditions. Besides trifluoroacetic anhydride, benzoyl bromide and ethylidenemalonate also reacted with the intermediate. This reaction enables both cyclization and introduction of their carbon-side chain of the cyclized intermediates in one-pot.Organomanganates did not react with Lewis acid at lower temperature, and this mixture of organomanganate and Lewis acid converted acetals to the corresponding substitution product. Ketal also reacted with the "mixed reagent".It was also found that alkyllithium reagents reacted with conjugated diynes in the presence of iron catalyst to give alkylated conjugated enynes. Alkylmagnesium reagents also afforded alkylated enynes. Interestingly, in the reaction of alkyllithium, the addition reaction proceeded in a manner of cis-addition, while the corresponding adduct, vinyilithium species isomerized to a cis-trans mixture under the equilibrium. When an ether functional group was in the diyne substrate, only trans-adduct was obtained, suggesting complete shift of the equilibrium to trans-adduct. Interestingly, Grignard reagents afforded only cis-adduct even in the reaction of diyne bearing an ether moiety. These vinyllithium and magnesium intermediates were very reactive, and reacted even with DMF and oxirans.