端基差向異構又稱為首旋異構物,一般存在於糖類中,是差向異構的一種,兩個非對映異構體分子(異頭物)的差異在於糖類環形結構半縮醛/半縮酮碳原子(異頭碳)的構型不同。1號碳的羥基若與5號碳的羥甲基處於哈沃斯透視式平面的兩側,則定義為α-異構體,反之稱為β-異構體。吡喃葡萄糖的兩種端基差向異構體可分別稱為「α-D-吡喃葡萄糖」和「β-D-吡喃葡萄糖」。
α-異構體與β-異構體的互相轉化稱為變旋現象。α-異構體受端基異構效應影響而得到穩定。
參見
外部連結
- Chin. Chem. Soc., Vol. 46(3) 283 (1999) (頁面存檔備份,存於網際網路檔案館) On the Assignment of Anomeric Configuration (pdf)
- http://arquivo.pt/wayback/20160516074319/http://www.cem.msu.edu/~reusch/VirtualText/carbhyd.htm
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