Stereochemical studies of alkyl methylcyclohexaneacetates with 13C NMR spectroscopy in relation to their attractiveness to the german cockroach.
作者:Yoshiaki IIDA、Ryozo SUGAWARA
DOI:10.1271/bbb1961.45.1553
日期:——
All positional isomers of methyl methylcyclohexaneacetates were prepared. Their diastereomeric pairs were separated from one another by preparative GLC. Either the cis or trans configuration was assigned to each of these GLC fractions on the basis of the chemical shift values of the ring methyl carbons in their 13C NMR spectra, which were found closely approximate to those of the corresponding dimethylcyclohexanes. The conformational compositions of the thermodynamically less stable diastereomers were determined using the chemical shift values of the axial and equatorial methyl carbons as parameters. The isomers of propyl methylcyclohexaneacetates for the biological test were separated similarly, and their configurations were determined by comparing the shift values of their ring methyl carbons with those of the methyl esters. The relative activity between the diastereomeric pairs was evaluated by a comparative trap test. The result was : cis-4-methyl isomer > trans-4-methyl isomer; trans-3-methyl isomer > cis-3-methyl isomer; and, trans-2-methyl isomer > cis-2-methyl isomer. The cis-4-methyl isomer exhibited activity comparable to that of the parent compound.
所有的甲基甲基环己酸酯的空间异构体被合成出来。它们的非对映异构体对通过制备气相色谱分开。根据它们的13C NMR光谱中环甲基碳的化学位移值,分别将顺式或反式构型分配给这些气相色谱分馏,这些值与相应的二甲基环己烷的值非常接近。通过使用轴向和赤道甲基碳的化学位移值作为参数,确定了热力学上不太稳定的非对映异构体的构象组成。用于生物测试的丙基甲基环己酸酯异构体也以类似方式分开,并通过将其环甲基碳的位移值与甲基酯的值进行比较来确定其构型。通过比较捕获测试评估了非对映异构体对之间的相对活性。结果是:顺式-4-甲基异构体 > 反式-4-甲基异构体;反式-3-甲基异构体 > 顺式-3-甲基异构体;反式-2-甲基异构体 > 顺式-2-甲基异构体。顺式-4-甲基异构体展现出的活性与母体化合物相当。