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Method for producing 2,5-substituted tetrahydropyran derivatives by reductive elimination of the corresponding 4-halogen derivative

A technology of tetrahydropyran derivatives and halogens, which is applied in the direction of organic chemistry, can solve the problems of low convergence and divergence, and achieve high chemical and stereoselective effects, simple methods, and good yields

Active Publication Date: 2011-10-19
MERCK PATENT GMBH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this synthesis has low convergence and divergence, and using disubstituted homoallylic alcohols it is only possible to prepare precursors of 2,5-disubstituted tetrahydropyran derivatives with only a very restricted structural range

Method used

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  • Method for producing 2,5-substituted tetrahydropyran derivatives by reductive elimination of the corresponding 4-halogen derivative
  • Method for producing 2,5-substituted tetrahydropyran derivatives by reductive elimination of the corresponding 4-halogen derivative
  • Method for producing 2,5-substituted tetrahydropyran derivatives by reductive elimination of the corresponding 4-halogen derivative

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0126] Example 1: GWP 1 - Reductive Elimination in the Presence of Heterogeneous Catalysts and Trialkylamines

[0127]The brominated substrate of formula II is dissolved in sufficient tetrahydrofuran (about 4 to 12 times the volume or weight of the compound of formula II) to add 10 to 30 wt%, preferably 20 wt% (corresponding to about 0.5 wt% based on II -6 mol% palladium) of 5% palladium on carbon (55% water), 2.5 molar equivalents of triethylamine and twice the amount of water (based on the substrate), the mixture was used in a pressurized autoclave Hydrogenation is carried out with hydrogen at a pressure of 4 to 6 bar up to the theoretical absorption of hydrogen. After cooling, the reaction mixture was filtered, and the filtrate was poured on ice, and the pH was adjusted to 1 with concentrated hydrochloric acid. The mixture was extracted once each with heptane and once with a heptane / toluene mixture. The combined organic phases were washed 4 times with water, dried and eva...

Embodiment 2

[0129] Example 2: Reductive Elimination Using Tributyltin Hydride

[0130]

[0131] 18.5 g (0.05 mol) of 4-chlorotetrahydropyran II-a were heated together with 32 g (0.11 mol) of tributyltin hydride and 0.81 g (5 mmol) of azobisisobutyronitrile in 500 ml of benzene under reflux 24 hours. The solvent is then evaporated off and the residue is taken up in 200 ml of methyl tert-butyl ether (MTBE). 232 ml of 10% aqueous KF solution (0.4 mol KF) and 1.08 g (2.5 mmol) of 18-crown-6 were added and the mixture was mixed vigorously. The organic phase is dried, evaporated, filtered through silica gel with heptane / toluene (9:1) and the residue obtained after evaporation is recrystallized from heptane. Yield of I-a (without optimization): 8.7 g (52%, 100% all-equivalent isomer).

[0132] C55I.

Embodiment 3

[0133] Example 3: Reductive Elimination Using Tris(trimethylsilyl)silane (TTMSS)

[0134]

[0135] 20.75 g (0.05 mol) of 4-bromotetrahydropyran II-b in 600 ml of 1,2-dimethoxyethane was mixed with 1.24 g (5 mmol) of TTMSS and 9.5g (0.25mol) of NaBH 4 Together, after adding 60 mg (2 mmol) of p-methoxybenzoyl peroxide, they were irradiated with light having a wavelength of 254 nm for 12 hours. The solvent was then essentially evaporated off in vacuo and the residue was filtered through silica gel with heptane / silica gel. Evaporation and recrystallization from heptane afforded I-b; yield (without optimization): 8.1 g (48%, 100% all-equivalent isomer).

[0136] C58I.

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Abstract

The invention relates to a method for producing the tetrahydropyran derivatives of formula (I), characterized by subjecting a tetrahydropyran derivative of formula (II) to a reductive elimination of substituent X<1>, wherein X<1> represents chlorine, bromine or iodine. The remaining substituents are defined in the claims.

Description

technical field [0001] The present invention relates to a method for preparing tetrahydropyran derivatives from halogenated tetrahydropyran derivatives and precursors thereof. Background technique [0002] Compounds having a tetrahydropyran ring as the central part of the molecule play an important role in organic chemistry, for example as constituents of natural or synthetic fragrance substances, pharmaceuticals or mesogenic or liquid crystal compounds, or as useful substances for the synthesis of these precursor. [0003] Of particular interest here are mesogenic or liquid crystalline tetrahydropyran derivatives with suitable (mesogenic) substituents, rings and / or ring systems at the 2- and / or 5-position, since they have some Favorable electro-optical and other physical properties for liquid-crystalline media. Therefore, there is a fundamental need for extremely simple and efficient synthetic methods which additionally make available a structurally very diverse variety o...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07D309/08
CPCC07D309/04C07D309/06C07D309/08
Inventor E·珀奇W·宾德尔S·莱曼D·本辛格
Owner MERCK PATENT GMBH
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