Synthesis of a Phosphonic Acid Analogue ofN-Acetyl-2,3-didehydro-2-deoxyneuraminic Acid, an Inhibitor ofVibrio cholerae Sialidase
作者:Andrea Vasella、Ren� Wyler
DOI:10.1002/hlca.19910740223
日期:1991.3.13
The synthesis of the phospha analogue 10 of DANA (2) is described. Bromo-hydroxylation of the known 11 ( 12 and 13) followed by treatment of the major bromohydrin 13 with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) gave the oxirane 14 (Scheme 1). Depending on the solvent, TiBr4 transformed 14 into 16 or into a 15/16 mixture. Reductive debromination of 16 ( 17), followed by benzylation provided 18. Oxidattve
描述了DANA(2)的磷酸酯类似物10的合成。已知11(12和13)的溴羟基化,然后用1,8-二氮杂双环[5.4.0]十一碳-7-烯(DBU)处理主要的溴代醇13,得到环氧乙烷14(方案1)。取决于溶剂,TiBr 4转化14至16或进入15 / 16混合物。还原脱溴化16(17),然后进行苄基化,得到18。通过18的皂化获得的酸的氧化脱羧(Pb(OAc)4)产生异头乙酸酯19和20。而19是惰性phosphonoylation的条件下,更具反应性的亚氨酸酯22,以一起获得23从19 / 20经由21(方案2),得到膦酸酯的混合物,24 / 25和双环缩醛26。去苄基化24 / 25和乙酰化导致acetoxyphosphonates 27/ 28。由于从AcOH中的β消去27 / 28被证明是困难,溴化物34制备自27 / 28通过photobromination并进行还原消除用Zn / Cu的(35