Isomerization method

A technology of compounds, carbon atoms, applied in the field of isomerization

Active Publication Date: 2011-06-22
MERCK PATENT GMBH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The application of this chemical property to the cis / trans stereochemistry of 1,4-substituted cyclohexanes has not been studied so far

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0058]

[0059] 20 g of starting material (64 mmol, 44% cis on central ring) were dissolved in 90 g of anhydrous dichloromethane (for analysis) and cooled to -45°C. 2 g of trifluoromethanesulfonic acid (13 mmol, 1.2 ml) were added to the suspension. Then 0.15 g of 1-adamantanol (1.0 mmol) in 9 g of dichloromethane was added dropwise. The batch was stirred at -40 to -45°C for an additional 1 to 3 hours, with occasional samples taken to measure the degree of isomerization. When isomerization was complete (sample was completely isomerized after 1-2 hours), the batch was processed.

[0060] For work-up, 38 ml of water were added to the batch, which was then warmed to about 20°C. The organic phase was separated off, washed with 22 g of trisodium citrate solution (25% in water) and 2×20 ml of water and evaporated to dryness in a rotary evaporator. The residue (20.2 g) was taken up in heptane and evaporated again. The crude product (pale yellow crystals) had a cis / trans conten...

Embodiment 2

[0063]

[0064] 168 g of starting material (525 mmol, 59.3% cis on central ring) were dissolved in 650 ml of anhydrous dichloromethane (for analysis) and cooled to -40 / -45°C. 9.5 ml of trifluoromethanesulfonic acid (108 mmol) were added to the suspension. 1.26 g of 1-adamantanol (8.3 mmol) in 50 ml of dichloromethane were then added dropwise. The batch was stirred at -40 to -45°C for an additional 1 to 2 hours, with occasional samples taken to measure the degree of isomerization. When isomerization was complete (sample was completely isomerized after 30 minutes), the batch was processed.

[0065] For work-up, a mixture of 175 g of ice and 350 ml of 25% hydrochloric acid was added to the batch, which was then warmed to about 20°C. The organic phase is separated off, washed with 175 ml of sodium bicarbonate solution (5% in water) and 175 ml of water and evaporated to dryness in a rotary evaporator. The residue (168.8 g) was taken up in heptane. The crude product (pale yel...

Embodiment 3

[0068] Example 1 was repeated while exchanging the catalyst 1-adamantanol for an equivalent amount of 2-chloro-2-methylpropane.

[0069] The crude product (pale yellow crystals) had 1.1% cis / trans product content, and 97.9% desired trans / trans product content (HPLC).

[0070] Other combinations of embodiments and variants of the invention can be derived from the claims.

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Abstract

The present invention relates to a method for preparing a trans-1,4-disubstituted cyclohexane compound with at least one benzene-derived residue at 1- or 4- position. The method comprises an isomerization step for converting one or a plurality of cis-configured cyclohexane ring to trans configuration in the presence of additional compound which forms carbocations while a strong acid is used.

Description

technical field [0001] The present invention relates to a process for the preparation of trans-1,4-disubstituted cyclohexane compounds having at least one residue derived from benzene in the 1- or 4-position, which process comprises the use of a strong acid and in the additional formation An isomerization step that converts one or more cis-configured cyclohexane rings to trans-configuration in the presence of a carbocationic compound. Background technique [0002] Functional chemicals are influenced not only by the functional groups present in them, but also to a crucial extent by their stereochemistry, ie their spatial structure. An important local field of stereochemistry focuses on simple nonaromatic rings and the relative positions of substituents on these rings. [0003] A fundamental issue in stereochemistry is the cis / trans isomerism of substituents on cyclohexane. The isomerization phenomenon of 1,4-substituted cyclohexane derivatives will be specifically discussed...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C17/358C07C25/18
CPCC07C5/2233C07C2527/053C07C13/28
Inventor D·马亚尔M·克里格鲍姆A·韦希特勒P·克拉蒂格R·谢弗
Owner MERCK PATENT GMBH
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