Parallel Solid-Phase Synthesis using a New Diethylsilylacetylenic Linker and Leading to Mestranol Derivatives with Potent Antiproliferative Activities on Multiple Cancer Cell Lines.

BACKGROUND: RM-133 belongs to a new family of aminosteroid derivatives demonstrating interesting anticancer properties, as confirmed in vivo in four mouse cancer xenograft models. However, the metabolic stability of RM-133 needs to be improved. After investigation, the replacement of its androstane scaffold by a more stable estrane scaffold led to the development of the mestranol derivative RM-581. METHODS: Using solid-phase strategy involving five steps, we quickly synthesized a series of RM-581 analogs using the recently-developed diethylsilylacetylenic linker. To establish structure-activity relationships, we then investigated their antiproliferative potency on a panel of cancer cell lines from various cancers (breast, prostate, ovarian and pancreatic). RESULTS: Some of the mestranol derivatives have shown in vitro anticancer activities that are close to, or better than, those observed for RM-581. Compound 23, a mestranol derivative having a ((3,5-dimethylbenzoyl)- L-prolyl)piperazine side chain at position C2, was found to be active as an antiproliferative agent (IC50 = 0.38 ± 0.34 to 3.17 ± 0.10 µM) and to be twice as active as RM-581 on LNCaP, PC-3, MCF-7, PANC-1 and OVCAR-3 cancer cells (IC50 = 0.56 ± 0.30, 0.89 ± 0.63, 1.36 ± 0.31, 2.47 ± 0.91 and 3.17 ± 0.10 µM, respectively). CONCLUSION: Easily synthesized in good yields by both solid-phase organic synthesis and classic solution-phase chemistry, promising compound 23 could be used as an antiproliferative agent on a variety of cancers, notably pancreatic and ovarian cancers, both having very bad prognoses.

Improved synthesis of mestranol and ethinyl estradiol (EE) related degradation products as authentic references.

Preparative chemical methods for the synthesis of 10 degradation or photodecomposition products of mestranol and ethinyl estradiol (EE) are described. The synthesized compounds are useful as reference materials and standards for pharmaceutical analysis of mestranol and EE as bulk chemical or in formulated product. New synthetic methods were presented and the known synthetic procedures were improved. Detailed structural characterization of the degradation or photodecomposition products of mestranol and EE and related compounds was reported.

A novel chromium(0)-promoted four-component cycloaddition reaction.

[formula: see text] Reaction of (eta 6-thiepin-1,1-dioxide)tricarbonylchromium(0) with excess terminal alkynes under photoactivation conditions affords novel pentacyclic adducts formally derived from a sequential [6 pi + 2 pi]/[6 pi + 2 pi]/[2 sigma + 2 pi] cycloaddition process.

Synthesis and estrogenic properties of 17-epi-ethynylestradiol and its ether derivatives epimestranol and epiquinestrol.

The synthesis of 17-epi-ethynylestradiol (10), the 17 beta-ethynyl-17 alpha-ol epimer of the well-known orally active estrogen, ethynylestradiol (1), was achieved by LiA1H4 reduction of epoxide 9, as well as by demethylating epimestranol (11) with CH3MgI. Compound 11 was obtained by the unusual 17 beta-ethynylation of estrone 3-methyl ether 22 under equilibrating conditions. The in vitro estrogen receptor-binding affinity and the oral estrogenicity in the rat for the 17-epi compounds 10, 11 and 20 (epiquinestrol) was evaluated. Despite moderate estrogen receptor-binding affinity, compound 10 was devoid of measurable estrogenicity at 10 mg/kg or antiestrogenicity at 3 mg/kg.

Lumi-mestranol and epi-lumi-mestranol.

Treatment of lumi-estrone 3-methyl ether (I) with acetylene gave the C-17-epimeric compounds lumi-mestranol (3-methoxy-17 alpha-ethynyl-13 alpha-estra-1,3,5(10)-trien-17 beta-ol, III ) and epi-lumi-mestranol (3-methoxy-17 beta-ethynyl-13 alpha-estra-1,3,5(10)-trien-17 alpha-ol, IV). The structures of the two isomers were assigned on the basis of their molecular rotations and shift-reagent experiments in the NMR. The irradiation of estrone 3-methyl ether (II) to provide compound I was investigated in two solvent systems. Minor products of these reactions were the seco-steroids VII, VIII and X.

Synthesis and biological evaluation of 2 - and 4- hydroxymestranol.

The synthesis of 2-hydroxy and 4-hydroxymestranol by oxidation of mestranol with m-chloroperbenzoic acid is described. The oral estrogenicity and contragestational activity of these and related catechol estrogen derivatives in the rat is also presented.

Preparation of 9-alpha,11-xi-tritiated 17-alpha-ethynylestradiol, mestranol, estradiol-alpha-17-beta, and norethindrone.

PIP: The preparation of 9alpha, 11xi-tritiated 17alpha-ethinyl estradiol, mestranol, estradiol-17beta, and norethindrone are described. Estrone-3-methyl ether was employed as starting material, and ethinylation with lithium acetylide-ethylene diamine resulted in 95% mestranol. Demethylation of mestranol with boron tribromide at 0 degrees resulted in 92% 17alpha-ethinyl estradiol. Dimethylsulfoxide was the choice of reagent for the condensation reaction which was complete at room temperature in about 4 hours. The usually less than 3% of unreacted 17-oxo product was removed by Girard separation. Demethylation of methyl ether with boran tribromide in methylene chloride resulted in an excellent yield of 17alpha-ethinyl estradiol-9alpha, 11xi-tritium. 3-methoxyestra-1,3,5-trien-17-one-9alpha, 11xi-tritium was reduced with sodium bis(2-methoxyethoxy) aluminum hydride to the 17beta-hydroxy compound and subsequent demethylation resulted in estradiol-9alpha, 11xi-tritium. The general method of Ringold et al was employed for the preparation of 17beta-hydroxy-17alpha-ethinylestr-4-en-3-one. Improvements for small scale radiosynthesis are also presented.^ieng