In:
Chirality, Wiley, Vol. 32, No. 1 ( 2020-01), p. 107-119
Abstract:
New xylal‐ and arabinal‐based monoaza‐15‐crown‐5 ethers were synthesized starting from l ‐ and d ‐xylose, and l ‐ and d ‐arabinose, respectively. These monosaccharide‐based chiral macrocycles were tested as phase transfer catalysts in a few asymmetric reactions. The xylal‐based crown compounds proved to be efficient catalysts in a few liquid‐liquid phase reactions. The epoxidation of trans ‐chalcone and the Darzens condensation of α‐chloroacetophenone with benzaldehyde took place with complete diastereoselectivity and up to 77% ee and 58% ee, respectively. It was found that the substituents in the aromatic ring of the chalcone and the α‐chloroacetophenone had an influence on the enantioselectivity. The highest ee values were obtained in the epoxidation of 4‐chlorochalcone (81% ee) and in the reaction of a 2‐naphthyl analogue (96% ee), while in the Darzens condensation of 4‐phenyl‐α‐chloroacetophenone with benzaldehyde, a maximum ee of 91% was detected. The configuration of the monosaccharide unit in the crown ring influenced the absolute configuration of the epoxyketones synthesized.
Type of Medium:
Online Resource
ISSN:
0899-0042
,
1520-636X
Language:
English
Publisher:
Wiley
Publication Date:
2020
detail.hit.zdb_id:
2001237-8
SSG:
12
SSG:
15,3
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