Time dependent efficiency of optical resolution of aminooxiranes with O,O'-dibenzoyl-(R,R)-tartaric acid

Faigl, Ferenc; Thurner, Angelika; Farkas, Ferenc; Proszenyák, Ágnes; Valacchi, Michela; Mordini, Alesandro

doi:10.3998/ark.5550190.0005.705

Cited by 2 publications

(1 citation statement)

References 7 publications

(11 reference statements)

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“…Given these results, it is rational to consider optimizing the current process, which is likely to be under kinetic control, since we discovered a new crystal form, (1 R ,2 S )- 1 ( S )-mandelate-II, which possesses completely different physical properties from the pre-existing (1 R ,2 S )- 1 ( S )-mandelate-I. Therefore, we concluded that the newly formed (1 R ,2 S )- 1 ( S )-mandelate-II made it impossible to selectively precipitate any of the crystal forms under kinetic control, and it would be better to change the strategy to develop a process under thermodynamic control. , This seemed possible; however, it was extremely difficult owing to the low difference in solubility (∼1.5–2 fold) between (1 S ,2 R )- 1 ( S )-mandelate and (1 R ,2 S )- 1 ( S )-mandelate-II …”

Section: Resultsmentioning

confidence: 95%

Practical Isolation of tert-Butyl [(1S,2R)-2-Aminocyclohexyl]carbamate (R)-Mandelate through Diastereomeric Salt Formation under Thermodynamic Control

Yamamoto

Yaji

Itô

2022

Org. Process Res. Dev.

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A practical method for isolating tert-butyl [(1S,2R)-2-aminocyclohexyl]carbamate ((1S,2R)-1) in its pure form was investigated. Two different patents from different groups have shown that (1S,2R)-1 can be isolated in the pure form using either (S)-mandelic acid or (R)-mandelic acid as a chiral resolving reagent. Our investigation revealed that both (1S,2R)-1 and (1R,2S)-1 form crystals with (S)-mandelic acid, and the latter salt has two crystal forms with different physicochemical properties including the solubilities and the crystal form transformation. The detailed physicochemical studies on the three crystal forms revealed that the patented processes proceed under kinetic control, which is not easy to manage on a large scale. Our process optimization based on the three crystal form behaviors led to the establishment of a process for manufacturing either (1S,2R)-1 (R)-mandelate or (1R,2S)-1 (S)-mandelate from commercially available cis-1,2-diaminocyclohexane. The newly developed process is considered to proceed under thermodynamic control and has been demonstrated on a large scale.

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Section: Resultsmentioning

confidence: 95%

Practical Isolation of tert-Butyl [(1S,2R)-2-Aminocyclohexyl]carbamate (R)-Mandelate through Diastereomeric Salt Formation under Thermodynamic Control

Yamamoto

Yaji

Itô

2022

Org. Process Res. Dev.

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Effect of ultrasound-assisted crystallization in the diastereomeric salt resolution of tetramisole enantiomers in ternary system with O,O′-dibenzoyl-(2R,3R)-tartaric acid

Szeleczky

Kis-Mihály

Semsey

et al. 2016

Ultrasonics Sonochemistry

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The diastereomeric salt resolution of racemic tetramisole was studied using ultrasound irradiation. We examined the effect of power and duration of ultrasonic irradiation on the properties of the crystalline phase formed by ultrasound-assisted crystallization and the result of the whole optical resolution. The results were compared with reference experiment without using ultrasound. The US time (5-30min) caused higher enantiomeric excess. Although yield was lower continuously high resolving efficiency could have been reached through ultrasound. We had the best results with 4.3W ultrasound power when resolvability was even higher than the best of reference. Furthermore, we accomplished a deep and thorough examination of the salts that possibly could form in this resolution. One of the four diastereomeric salts, which have been identified by powder X-ray diffraction, FTIR-spectroscopy, and differential scanning calorimetry (DSC) in the ternary system of the two tetramisole enantiomers and the resolving agent, namely the bis[(S)-tetramisole]-dibenzoyl-(R,R)-tartrate salt have been proven the key compound in the resolution process, and presented the highest melting point of 166°C (dec.) among the four salts. The originally expected diastereomeric bitartrate salts with 1:1M base:acid ratio [(S)-tetramisole-dibenzoyl-(R,R)-hydrogen-tartrate salt and (R)-tetramisole-dibenzoyl-(R,R)-hydrogen-tartrate salt] and their 'racemic' co-crystal [(RS)-tetramisole-dibenzoyl-(R,R)-hydrogen-tartrate salt] showed somewhat lower melting points (152, 145, and 150°C, respectively) and their crystallization was also prevented by application of ultrasound. Based on the melting points and enthalpies of fusion measured by DSC, all the binary and ternary phase diagrams have been newly established and calculated in the system with help of classical modelling equations of liquidus curves.

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Time dependent efficiency of optical resolution of aminooxiranes with O,O'-dibenzoyl-(R,R)-tartaric acid

Cited by 2 publications

References 7 publications

Practical Isolation of tert-Butyl [(1S,2R)-2-Aminocyclohexyl]carbamate (R)-Mandelate through Diastereomeric Salt Formation under Thermodynamic Control

Practical Isolation of tert-Butyl [(1S,2R)-2-Aminocyclohexyl]carbamate (R)-Mandelate through Diastereomeric Salt Formation under Thermodynamic Control

Effect of ultrasound-assisted crystallization in the diastereomeric salt resolution of tetramisole enantiomers in ternary system with O,O′-dibenzoyl-(2R,3R)-tartaric acid

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