Synthesis of ribo-hexopyranoside- and altrose-based azacrown ethers and their application in an asymmetric Michael addition

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• 作者：Zsolt Rapi^a ; Pé ; ter Bak&#243 ; ^a ; ^{pbako@mail.bme.hu} ; Gyö ; rgy Keglevich^a ; Á ; ron Szö ; llő ; sy^b ; Lá ; szl&#243 ; Drahos^c ; Lá ; szl&#243 ; Hegedű ; s^d
• 关键词：Sugar-based chiral crown ethers ; Anhydro sugars ; Asymmetric Michael addition ; Enantioselectivity
• 刊名：Carbohydrate Research
• 出版年：2013
• 出版时间：10 January, 2013
• 年：2013
• 卷：365
• 期：Complete
• 页码：61-68
• 全文大小：626 K

文摘

The synthesis of four new ribo-hexopyranoside-based chiral lariat ethers of monoaza-15-crown-5 type and two altropyranoside-based crown ethers were elaborated. Our syntheses utilized the regioselective ring opening of the oxiran moiety of the 2,3-anhydro sugars by nucleophilic reagents to afford the key intermediates. The reaction of methyl-2,3-anhydro-4,6-O-benzylidene-¦Á-d-mannopyranoside with ethanolamine is especially of interest to afford a 3-substituted altropyranoside. One of the ribo-hexopyranoside-based lariat ethers with a 4-methoxyphenyl substituent induced an enantioselectivity of 80 % when used as catalyst in the Michael addition of diethyl acetamidomalonate to trans-¦Â-nitrostyrene under phase transfer catalytic conditions.