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Prostaglandin synthesis and intermediates for use therein

a technology of prostaglandin and analog, which is applied in the field of prostaglandin analog and its synthesis, can solve the problems of difficult synthesizing of prostaglandin analog, limited range of industrially acceptable reagents, solvents, catalysts, etc., which can be used in their synthesis, and complications

Inactive Publication Date: 2011-05-12
ALPHORA RES
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

This method reduces the synthesis of lubiprostone to eight steps with an overall yield exceeding 15%, significantly higher than prior art processes, while maintaining stereospecificity and using relatively inexpensive reagents, resulting in a highly crystalline product with improved pharmaceutical potential.

Problems solved by technology

Prostaglandin analogs are difficult to synthesize.
Complications arise because of the requirements of the end products to have several functional groups and two side chains of significant size and complexity.
Since the products are intended for pharmaceutical use, the range of industrially acceptable reagents, solvents, catalysts, etc. which can be used in their synthesis is limited to those having pharmaceutical industry acceptability.
Inevitably, such a multi-step process is time consuming and expensive to conduct, and results in relatively low overall yield of final product.
The synthesis of lubiprostone presents significant technical challenge because of the chemical complexity of the fluorine containing substituent chain at the 12-position.
Known methods for its synthesis suffer from the aforementioned disadvantages, namely a multi-step (typically 15-step) synthesis from Corey alcohol with consequent low yields of final product and time consuming nature of the process.

Method used

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  • Prostaglandin synthesis and intermediates for use therein
  • Prostaglandin synthesis and intermediates for use therein
  • Prostaglandin synthesis and intermediates for use therein

Examples

Experimental program
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Effect test

example 1

[0031]

[0032]Corey Lactone Diol 12. To a suspension of 10 (15 g, 54 mmol, 1 equiv) in methanol (75 mL) was added sodium methoxide (25% wt in methanol, 1.2 mL, 5.4 mmol, 0.1 equiv). The mixture was stirred at room temperature for 1.5 h and then hydrochloric acid solution (4 M in dioxane, approximately 1 mL) was added until the pH was 3-4. The solution was stirred at room temperature for 10 min and then concentrated to dryness under vacuum on a rotary evaporator. The resulting white solid was suspended in methyl tert-butyl ether (150 mL) and stirred at room temperature for 1 h. The solid was filtered, washed with methyl tert-butyl ether, and dried under vacuum for 10 min to afford 9.1 g of 12 (97%) as a white solid.

[0033]Protected Diol 16. To a suspension of 12 (5.0 g, 29 mmol, 1 equiv) in toluene (100 mL) was added anisaldehyde dimethyl acetal (14) (7.4 mL, 44 mmol, 1.5 equiv) and p-methoxy benzoic acid (44 mg, 0.29 mmol, 0.01 equiv). A condenser and a Dean-Stark apparatus were attach...

example 2

[0044]Protected lubiprostol compound 28, prepared as described in Example 1, was deprotected by hydrogenation in mixed ethanol / 2-propanol, and crystallized from isopropyl acetate.

[0045]To a thick walled clear Pyrex Reaction Bottle was added under a flow of nitrogen palladium on carbon (10% wt on carbon, 50% wt in water, 1.07 g, 0.1 equiv, 0.503 mmol). Ethanol / 2-propanol (1:4 v / v, 18 mL, 6 parts) was added under a flow of nitrogen. A mixture of compound 28 (3 g, 5.03 mmol, 1 equiv) in ethanol / 2-propanol (1:4 v / v, 51 mL, 17 parts) was added under a flow of nitrogen. The flask was rinsed with ethanol / 2-propanol (1:4 v / v, 6 mL, 2 parts). The mixture was shaken in a Parr shaker at 40 psi at room temperature for 24 h. The mixture was purged with nitrogen, filtered through Celite (15 g, 5 parts), and washed with ethanol / 2-propanol (1:4 v / v, 75 mL, 25 parts). The solution was concentrated to dryness under vacuum on a rotary evaporator at 45° C. The resulting yellow oil was dissolved in dich...

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Abstract

Fused cyclopentane-4-substituted 3,5-dioxalane lactone compounds useful as an intermediate in the synthesis of prostaglandin analogs are provided. The compounds have the formula A:wherein R represents an aryl group such as p-methoxyphenyl.This compound can be reacted with a lower alkyl aluminum compound to open the dioxalane ring and reduce the lactone to lactol, without over-reducing to diol. The resulting compound can be functionalized to insert chemical side groups of target prostaglandins, adding the required α-side chain and then the required ω-side chain sequentially and independently of each other. The compounds and process are particularly suitable for preparing lubiprostone.

Description

FIELD OF THE INVENTION[0001]This invention relates to prostaglandin analogs and their synthesis. More particularly, it relates to a novel, simplified synthesis of prostaglandin analogs, and novel chemical compounds useful as intermediates in such synthesis.BACKGROUND OF THE INVENTION AND PRIOR ART[0002]Prostaglandins (PGs) are organic carboxylic acids, namely cyclopentanes carrying two side chain substituents, typically linear C6-C8 side chains, bonded to adjacent positions on the cyclopentane nucleus. One of the side chains, the α-side chain, carries a terminal carboxylic acid group. Many are natural products found in mammalian organs and tissues (primary PGs), and exhibit a variety of physiological activities. Primary PGs generally have a prostanoic acid skeleton, which forms the basis of the nomenclature: α[0003]A significant number of synthetic PG analogs have been made and found to have useful pharmacological properties. These may have modified skeletons, and substituted and un...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C07D311/94C07D493/04C07D307/935C07C69/738
CPCC07C405/00C07C2101/08C07D307/935C07D307/937C07D493/04C07C59/90C07D311/94C07C2601/08
Inventor ALBERICO, DINOCLAYTON, JOSHUAGORIN, BORIS IVANOVICHOUDENES, JAN
Owner ALPHORA RES
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