第五丶六族元素的有机化合物在有机合成中应用的研究 XVIII:氰基亚甲基三苯基胂与酮反应的立体化学以及几种吸电子基团取代的甲基三苯基 砷盐与酮的反应

The stereochemistry of carbonyl olefination reaction of cyanomethylene triphenylarsorane with ketones is reported. The thermodynamically stable E isomer of the products α, β unsaturated nitrile was formed predominantly. Under the experimental conditions we adopted, the reaction conditions had little effect on the E, Z ratio of the reaction products. However, the structure of the substrate showed profound effect. The results shown in Table 1 are similar to that of the reaction of carbomethoxymethylene triphenylarosorane reported in the previous paper. When methyl t-butyl ketone was used as the substrate and the reaction carried out in benzene solution, nearly pure E isomer was obtained. The reaction mechanism was proposed as shown in the previous paper. When Δ4-cholesten-3-one was used as the substrate, change of the solvents showed more prominent effect on the E, Z ratio of the reaction product. This paper also deals with the reaction of three electron-withdrawing group (CN, COOCH3, COCH3) substituted methyltriphenylarsonium salts with ketones in the presence of K2CO3, Na2CO3/benzo-15-crown-5, K2CO3/18-crown-6 or (C2H5)3N in CH3OH solution. The latter three gave satisfactory results (Table 2). The chromotographically pure products could be obtained from the crude products by passing through silica gel column. Its E, Z ratio is nearly the same as that of the crude product. This method seems to be a good one for preparing olefinic compounds in miligram scale.     

第五、六族元素的有机化合物在有机合成中应用的研究——Ⅸ.氰代亚甲基三苯基胂与酮的反应

Trippett^[1]曾报道氰代亚甲基三苯基膦不能与酮反应.作者之一及其同工作者曾报道甲氧羰基亚甲基三苯基胂与多种醛、酮反应,其反应性能比相应的膦试剂活泼.本文报道氰代亚甲基三苯基胂(2)的制备,以及它与一系列酮包括α,β-不饱和酮的反应(产物和产率列于表1),表明2的反应性能也较相应的膦试剂活泼.     

第五、六族元素的有机化合物在有机合成中应用的研究 ⅩⅧ.氰基亚甲基三苯基胂与酮反应的立体化学以及几种吸电子基团取代的甲基三苯基鉮盐与酮的反应

本文报道氰基亚甲基三苯基胂与七种酮反应的立体化学,除Δ~(4-)胆甾烯-3-酮外,其它六种酮与甲氧羰基亚甲基三苯基胂与酮反应的立体化学结果相似。另外还报道了三种吸电子基团取代的甲基三苯基鉮盐在弱碱或弱碱-冠醚存在下直接与酮的反应,粗产物经硅胶柱层析分离能得色谱纯产物,其E,Z异构体比例与粗产物中保持一致,操作简便,是目前制备毫克量烯烃的较好方法。