Synthesis of new 16-spirosteroids

Diversity-oriented synthesis of 17-spirosteroids

A diversity-oriented synthesis (DOS) approach has been used to functionalize 17-ethynyl-17-hydroxysteroids through a one-pot procedure involving a ring-closing enyne metathesis (RCEYM) and a Diels–Alder reaction on the resulting diene, under microwave irradiations. Taking advantage of the propargyl alcohol moiety present on commercially available steroids, this classical strategy was applied to mestranol and lynestrenol, giving a collection of new complex 17-spirosteroids.

Synthesis of novel 16-spiro steroids: 7-(Aryl)tetrahydro-1H-pyrrolo[1,2-c][1,3]thiazolo estrone hybrid heterocycles

The 1,3-dipolar cycloaddition of azomethine ylides generated in situ from the reaction of isatins or acenaphthylene-1,2-dione and 1,3-thiazolane-4-carboxylic acid to various exocyclic dipolarophiles synthesized from estrone afforded a library of novel C-16 spiro oxindole or acenaphthylene-1-one - 7-(aryl)tetrahydro-1H-pyrrolo[1,2-c][1,3]thiazole - estrone hybrid heterocycles. These reactions occur regio- and stereo-selectively affording a single isomer of the spiro estrones in excellent yields with the formation of two C-C and one C-N bonds along with the generation of four new contiguous stereo-centers in a single step.

Synthesis of novel 16-spiro steroids: spiro-7'-(aryl)tetrahydro-1H-pyrrolo[1,2-c][1,3]thiazolo-trans-androsterone hybrid heterocycles

The 1,3-dipolar cycloaddition of azomethine ylide derived in situ from the reaction of acenaphthylene-1,2-dione and 1,3-thiazolane-4-carboxylic acid to various exocyclic dipolarophiles synthesized from trans-androsterone and trans-dehydroandrosterone afforded a library of novel spiro[5'.2″]acenaphthylene-1″-one-spiro[16.6']-(7'-aryl)-tetrahydro-1H-pyrrolo [1,2-c][1,3]thiazolo-trans-androsterone/dehydroandrosterone hybrid heterocycles respectively. These reactions proceeded stereo-specifically affording a single isomer of the 16-spiro steroids in excellent yields.

Acid Catalysed Reaction of Estrones with Neopentyl Glycol under Forced Conditions

Upon reaction with an excess of 2,2-dimethylpropane-1,3-diol (neopentyl glycol) under acid catalysis, estrones form 17-O-[2′,2′-dimethyl-2′-(5″,5″-dimethyl-1″,3″-dioxanyl)ethyl] substituted estra-3, 17β-diols. The reaction represents a formal reduction of a keto function under acidic conditions in the absence of a metal.

A facile total synthesis of ent-17beta-estradiol and structurally related analogues

A facile six-step synthesis (15.2% yield) of ent-17beta-estradiol from readily accessible precursors is described. The preparation of analogues with 2-alkyl substituents, double bond unsaturation in the C-ring, a cis C,D-ring fusion and modified substituents at C(17) is also reported.

Androsterone derivatives substituted at position 16: chemical synthesis, inhibition of type 3 17beta-hydroxysteroid dehydrogenase, binding affinity for steroid receptors and proliferative/antiproliferative activity on Shionogi (AR+) cells

A series of androsterone (ADT) derivatives substituted at position 16 were efficiently synthesized in short reaction sequences; the ether analogues were also synthesized in the case of the methyl and allyl derivatives. The aim of this study was to develop inhibitors of the steroidogenic enzyme type 3 17beta-hydroxysteroid dehydrogenase and then evaluate their ability to inhibit this activity in transfected HEK-293 cells. For each compound we measured the percentage of inhibition of the transformation of 4-androstene-3,17-dione, the natural substrate of this steroidogenic enzyme, into the active androgen testosterone. The synthesized compounds proved to be weak inhibitors of this enzyme, but interestingly, these ADT derivatives do not bind to androgen, estrogen, glucocorticoid, and progestin receptors, suggesting no unsuitable receptor-mediated effects. One exception, 16alpha-(3'-bromopropyl)-5alpha-androstane-3alpha,17beta-diol, the only compound bearing a hydroxy group at position 17beta instead of a ketone, showed a strong binding affinity for the androgen receptor (70% at 1 microM) and also exhibited an antiproliferative activity on Shionogi (AR+) cells (86% at 1 microM), which was comparable to that of hydroxyflutamide, a pure antiandrogen (100% at 1 microM).

Neighboring group participation. Part 14. The preparation of the four stereoisomers of 16-hydroxymethyl-5alpha-androstane-3beta,17-diol

16alpha-Hydroxymethyl-5alpha-androstane-3beta,17beta-diol and 16beta-hydroxymethyl-5alpha-androstane-3beta,17beta-diol, were obtained from reduction of 16-acetoxymethylene-5alpha-androstan-17-one. The corresponding 16alpha,17alpha- and 16beta,17alpha-hydroxymethyl isomers were obtained by neighboring group participation of the 16- and 17-acetates, respectively. The reactions involving carbocation formation also led to ring D rearrangement products.

Synthesis of 16-(bromoalkyl)-estradiols having inhibitory effect on human placental estradiol 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD type 1)

The activity of 17 beta-HSD type 1, the enzyme that converts estrone into its more potent metabolite estradiol, has been demonstrated in all classical steroidogenic tissues and almost all peripheral tissues from both rat and human. Since 17 beta-HSD is one of the most important enzymes involved in active steroid hormone formation, its inactivation could be a clinical approach to the treatment of hormono-dependent diseases like breast cancer. Herein we report the synthesis of 16-(bromoalkyl)-estradiols and their potency to inhibit the human placenta cytosolic estradiol 17 beta-HSD (type 1). Synthetic analogues possess various side chain lengths and orientation (alpha or beta) at position 16 of the steroidal D ring. The most potent inhibitory effect was observed when the length of the side chain was 3 or 4 carbons. However, the 16 beta-(bromopropyl)-estradiol easily undergoes cyclization and its effect on 17 beta-HSD is lost. Consequently, 16 alpha-(bromopropyl)-E2, 16 alpha-(bromobutyl)-E2, and 16 beta-(bromobutyl)-E2 were the best inhibitors discussed in this paper.