Modified steroid hormones-XXXIII

Efficient Synthesis of 6-Substitued-3-aminoestrogens

“…常见的 6 位取代的甾体药物有抗癌药 exemestane (依西美坦)和避孕药 megestrol(甲地孕酮). 合成可通过 Vilsmeier 反应或 Mannich 反应在 C-6 位引入次甲基, 再 进一步转化获得 [6] . 但这些方法一般多用于甲基的导入, 通用性不强.…”

Preparation and progestational activity of 6-trifluoromethyl-16-methylene-17.alpha.-hydroxy-4,6-pregnadiene-3,20-dione 17-acetate and related compounds

“…Although 9 was not obtained in crystalline state, it could be converted directly to the desired 6. For larger scale preparations of 6, it wás decided to introduce the second double bond into 4 which already had the desired substituents in ring D (Scheme III). ft6a-Methyl-16-methylene-17a-hydroxy-4-pregnene-3,20-dione 17acetate; cf.…”

Reactions of Ortho Esters Which Result in Carbon-Oxygen and Carbon-Halogen Bond Formation

“…Hydrogen ion-catalyzed hydrolyses of triethyl orthoacetate and trimethyl and triethyl orthobenzoates have small positive entropies of activation (81,118,158). In aqueous solutions the catalytic coefficient ratio of hydrogen ion in heavy and ordinary water (k D +lk H +) is 1.4 for tetraethyl orthocarbonate hydrolysis (303), almost 2.3 for trimethyl and triethyl orthobenzoate hydrolysis (81,118) and about 2.7 for triethyl orthoformate hydrolysis (57). Rates of hydrolysis of trimethyl orthobenzoate (118) and tetraethyl orthocarbonate (165) are unaffected by added nucleophiles.…”

“…Ketalization by the orthoformate method is usually carried out by Claisen's original procedure (57), or a modification of it. He allowed mixtures of 1 mole of carbonyl compound, 1 mole of triethyl orthoformate, and 3 moles of alcohol to stand in the presence of an acid catalyst such as hydrogen chloride, ammonium chloride, or ferric chloride until equilibrium was attained, and then isolated the acetal or ketal.…”