Continuing our search for vitamin D analogues, we explored the modification of the steroidal side chain and inserted a methylene moiety in position C-22 together with either lengthening the side chain or introducing a ring at the terminal end. Our conformational studies confirmed that the presence of a methylene group attached to C-22 restricts the conformational flexibility of the side chain, which can result in changes in biological characteristics of a molecule. All synthesized 1α,25-dihydroxy-2,22-dimethylene-19-norvitamin D₃ analogues proved equal to calcitriol in their ability to bind to the vitamin D receptor, and most of them exert significantly higher differentiation and transcriptional activity than calcitriol. The most active compounds were characterized by the presence of an elongated side chain or 26,27-dimethylene bridge. The synthetic strategy was based on the Wittig–Horner coupling of the known A-ring phosphine oxide with the corresponding Grundmann ketones prepared from a 20-epi-Inhoffen-Lythgoe diol derived from vitamin D₂.

中文翻译：

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19-去甲三醇和相关化合物的2,22-二亚甲基类似物的合成和生物活性。

在继续寻找维生素D类似物的过程中，我们探索了甾体侧链的修饰方法，并在C-22位置插入了一个亚甲基部分，同时加长了侧链或在末端引入了环。我们的构象研究证实，连接至C-22的亚甲基的存在会限制侧链的构象柔韧性，从而导致分子生物学特性发生变化。所有合成的1α，25-二羟基-2,22-二亚甲基-19-正维生素D ₃类似物在结合维生素D受体的能力方面被证明与骨化三醇相同，并且大多数类似物比骨化三醇具有更高的分化和转录活性。活性最高的化合物的特征是存在细长的侧链或26,27-二亚甲基桥。合成策略基于已知的A环氧化膦的Wittig-Horner偶联与相应的Grundmann酮的偶联，所述酮由从维生素D ₂衍生的20-表位-Inhoffen-Lythgoe二醇制得。