A New Method for High Activation of Acyliminium Ions and Reactions with Group 14 Organometallic Reagents

在氮杂环中引入有用的功能化碳取代基的方法的发展对于合成各种具有生理和药理活性的氮杂环化合物具有重要意义。1996年的研究发现，喹啉经氯甲酸苯酯和三酸银处理后，生成了一个高度活化的n -酰基喹啉离子，并且产生的n -酰基喹啉离子很容易与烯丙基硅烷反应。此外，还发现异喹啉与烯丙基硅烷的反应与上述反应类似，得到了苯并异喹啉体系。在上述结果的基础上，本年度的主要目的是改进反应条件，以及利用除烯丙基硅烷以外的其他有机硅试剂进行反应，以便在氮杂芳烃中引入除烯丙基以外的其他有用的碳取代基。在本反应中，杂芳烃上的各种官能团，如酯、甲酰基、氰基、甲基苯甲酸和硝基都能被耐受，表现出较高的化学选择性，尽管在某些情况下收率较低。通过实验，发现乙腈是比二氯甲烷更好的溶剂，在几乎所有的反应中都能提高收率。这可能是由于n -酰基喹啉离子在极性较强的乙腈溶液中有利于形成。从环保的角度来看，使用非氯化溶剂是另一个优点。与2-甲基、2-氯甲基和2-三甲基硅氧基甲基烯丙基硅烷的反应也很容易得到高产量的加合物。-碳碱系统的反应也很有效。接着，研究了与烯基、丙炔基和炔基硅烷的反应。在乙腈中加入等摩尔量的三酸银时，烯基硅烷与丙烯基硅烷反应，产率高。在三氟化银的催化作用下，丙基硅烷与丙基硅烷的反应可得到烯化加合物，收率高。此外，在等摩尔量的三酸银存在下，在高温下与反应性较低的炔基硅烷进行反应，得到收率较高的炔基化加合物。少

Development of methodology for introduction of useful functional carbon substituents into nitrogen heterocycles is of great importance of synthesis of various physiologically and pharmacolotically active nitrogen heterocyclic compounds.It has been found in the studies during 1996 that a highly activated N-acylquinolinium ion is generated when quinoline is treated with phenyl chloroformate and silver triflate and that N-ccylquinoliun ion thus pwoduced can readily react with allylsilanes. It has been found, furthermore, that the similar reaction of isoquinoline with allylsilane to the above affords a benzoisoquinuclidine system.On the basis of the above results, major purposes in this year are focused on improvements of the reaction conditions as well as the reactions by means of other organosilicon reagents than allylsilane in order to introduce other useful carbon substituents than allyl group into nitrogen heteroaromatics.A variety of functional groups, such as ester, formyl, cyano, a … More nd nitro, on heteroaromatics are tolerated in the present reaction, showing the high chemoselectivity, though the yields are low in some cases. After the through experiments, acetnitrile has been found to the better solvent than dichloromethane, increasing the yields in almost all of the reactions. This could be ascribed to a favorable formation of N-acyl-quinolinium ion in more polar acetonitrile solution. Use of non-chlorinated solvent is another advantage from environmental point of view. The reactions with 2-methyl-, 2-chloromethyl-, and 2-trimethysiloxy-methylallylsilanes also readily proceed to give adducts in good yields. The reactions of beta-carboline system also work very well.Next, the reactions with allenyl-, propargyl-, and alkynylsilanes have been examined. It has been found that the reactions with allenylsilanes in the presence of equimolar amount of silver triflate in acetnitrile gives propargylated adducts in good yields. The reactions with propargylsilanes in presence of catalytic amount of silver triflate afford allenylated adducts in good yields. Furthermore, the reactions with less reactive alkynylsilanes are conducted in the presence of equimolar amount of silver triflate at elevated temperature to give alkynylated adducts in goond yields. Less