Synthesis of N,O-Type Inherently Chiral Calix[4]arenes Substituted on the Lower Rim and their Organocatalysis Properties

Chang, Ming-Liang; He, Yong; Zhou, Jian; Li, Shaoyong

doi:10.21577/0103-5053.20160307

Cited by 3 publications

(3 citation statements)

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“…But their use in asymmetric organocatalysis hasn’t been reported. To explore the organocatalytic behaviors of inherently chiral calix[4]arenes modified at the lower rim, Li et al reported the synthesis of N,O -type enantiomers based on inherently chiral calix[4]arene ( Scheme 5 ) [ 41 ]. The synthetic sequence starts from a pair of optically pure inherently chiral calix[4]arene diastereomers 16a/16b and contains four steps to lead 20a/20b as a pair of enantiomers.…”

Section: Reviewmentioning

confidence: 99%

Recent applications of chiral calixarenes in asymmetric catalysis

Durmaz

Halay

Bozkurt

2018

Beilstein J. Org. Chem.

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Section: Reviewmentioning

confidence: 99%

Recent applications of chiral calixarenes in asymmetric catalysis

Durmaz

Halay

Bozkurt

2018

Beilstein J. Org. Chem.

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“…The crude residue was loaded directly onto a silica gel column and purified by flash chromatography. The absolute configurations of all products were determined by comparing the retention time from HPLC data on the products with those in the literature data …”

Section: Methodsmentioning

confidence: 99%

Mononitration of a Calix[4]arene Methylene Bridge: Synthesis and Preliminary Catalysis Performances of Bridging Chiral p-tert-Butylcalix[4]arenes with a Monoamino Bridge Substituent in a 1,3-Alternate Conformation

Peng

Sun

et al. 2021

J. Org. Chem.

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In order to prepare bridging chiral p-tert-butylcalix[4]crown-5 with a mononitro bridge substituent in a 1,3-alternate conformation, a mononitration method of calix[4]arene bridging methylene has been first developed with tert-butyl nitrite as a nitration reagent. The effects of solvent, reaction temperature, reaction time, and nitration reagent dosage on bridge mononitration have been deeply explored to obtain an optimal nitration condition. The facile nitration presents a new key for calix[4]arene bridge derivatization. After further modification and diastereoisomeric resolution, a pair of bridging chiral p-tert-butylcalix[4]arenes with a monoamino bridge substituent were produced from the bridge-mono-nitrated calix[4]arene. Their preliminary catalysis results in the Henry reaction show good catalytic activities (up to 95% yield) and still low but obviously enhanced enantioselectivities (up to 22.3% ee from 7a, 6% ee from 1), which confirms that the structural transformation indeed improves asymmetric catalysis performances of bridging chiral calix[4]crown-5 amines in a 1,3-alternate conformation.

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“…[16] However, calixarene-derived PTCs for asymmetric Henry reaction is virtually absent in the literature. To the best of our knowledge, the only reported examples pertaining to calix [4]arene functionalized organocatalysts for Henry reaction are reported with poor enantioselectivities by Ma [17] (7.5 % ee) and Li [18] (22.3 % ee). Hence the design of effective PTCs for Henry reaction with high enantioselectivity under mild conditions remains the sine qua non to date.…”

Section: Introductionmentioning

confidence: 99%