Department of Organic Chemistry, Indian Institute of Science, Bangalore 560 012, India.
J Org Chem. 2012 Mar 2;77(5):2185-91. doi: 10.1021/jo202240f. Epub 2012 Feb 9.
A method to convert 2-hydroxy glycal ester to the corresponding 2-deoxy-2-C-alkyl glycal in a facile manner, through key reactions including (i) C-allylation at C-1, (ii) Wittig reaction, and (iii) Cope rearrangement of a 1,5-diene derivative, is reported. The α-anomer of the 1,5-diene derivative underwent Cope rearrangement to afford 2-deoxy-2-C-glycal derivative, whereas the β-anomer was found to be unreactive. Employing this sequence, 3,4,6-tri-O-benzyl-2-O-acetyl-1,5-anhydro-d-arabino-hex-1-enitol was transformed to 3,4,6-tri-O-benzyl-2-deoxy-2-C-alkyl-1,5-anhydro-D-arabino-hex-1-enitol. 2-Deoxy-2-C-alkyl glycal derivative is a suitable glycosyl donor to prepare 2-deoxy-2-C-alkyl glycosides, mediated through haloglycosylation and a subsequent dehalogenation. A number of 2-deoxy-2-C-alkyl glycosides, with both glycosyl and nonglycosyl moieties at the reducing end, are thus prepared from the glycal.
报道了一种简便的将 2-羟基糖醛酸酯转化为相应的 2-脱氧-2-C-烷基糖醛酸酯的方法，该方法涉及关键反应，包括 (i) C-1 位的烯丙基化、(ii)Wittig 反应和 (iii)1,5-二烯衍生物的 Cope 重排。1,5-二烯衍生物的α-异构体经历 Cope 重排，得到 2-脱氧-2-C-糖醛酸酯衍生物，而β-异构体则被发现没有反应活性。采用该序列，3,4,6-三-O-苄基-2-O-乙酰基-1,5-脱水-D-阿拉伯己-1-烯醇转化为 3,4,6-三-O-苄基-2-脱氧-2-C-烷基-1,5-脱水-D-阿拉伯己-1-烯醇。2-脱氧-2-C-烷基糖醛酸酯衍生物是一种合适的糖基供体，可通过卤代糖基化和随后的脱卤化作用制备 2-脱氧-2-C-烷基糖苷。因此，从糖醛酸酯制备了许多具有还原端糖基和非糖基部分的 2-脱氧-2-C-烷基糖苷。
