The gas chromatographic-mass spectrometric properties of diethylhydrogensilyl cyclic diethylsilylene derivatives of hydroxypregnanes were studied. Pregnanes with a sterically hindered 11β-hydroxyl group were smoothly silylated with a new silylating agent, N, O-bis(diethylhydrogensilyl)-trifluoroacetamide, under mild conditions. The mass spectra of these derivatives were characterized by the appearance of the intense molecular ion peak, which provides convenient and reliable confirmation of the molecular weight of these hydroxypregnanes. The most characteristic fragment ions were those at m/z 185 for 17, 20-diols and at m/z 287 for 17, 20, 21-triols, which were produced by cleavage at the C(13)-C(17) and C(15)-C(16) bonds with hydrogen atom transfer. This indicates that all of the major fragmentations are directed by the cyclic diethylsilylene group. Another fragmentation common to the spectra was the successive loss of diethylhydrogensilanol from the molecular ion. A remarkable difference in the appearance of peaks was observed between DEHS-DES derivatives of a 17α, 20α, 21-triol and its 20β-isomer. Structures are proposed for some of these fragment ions.
研究了羟基孕烷的
二乙基氢
硅烷基环
二乙基硅烷衍
生物的气相色谱-质谱特性。在温和的条件下,用一种新的
硅烷化剂 N, O-双(
二乙基氢代苯甲酰)-三
氟乙酰胺顺利地
硅烷化了带有立体受阻的 11β- 羟基的孕烷。这些衍
生物的质谱特征是出现了强烈的分子离子峰,这为确定这些羟基孕烷的分子量提供了方便可靠的依据。最有特征的碎片离子是 17、20
-二醇的 m/z 185 和 17、20、21-三醇的 m/z 287,它们是通过氢原子转移裂解 C(13)-C(17) 和 C(15)-C(16) 键产生的。这表明所有主要碎片都是由环状
二乙基硅基引导的。光谱中的另一个共同碎片是分子离子中的
二乙基氢
硅醇相继消失。在 17α、20α、21-三醇的 DEHS-DES 衍
生物与其 20β 异构体之间,观察到峰值出现的明显差异。提出了其中一些碎片离子的结构。