Synthesis of optically active 2-fluoroalk-1-en-3-yl esters and chirality transfer in their Claisen-type rearrangements
作者:Michael Marhold、Ulrich Wittmann、Stefan Grimme、Tamiko Takahashi、Günter Haufe
DOI:10.1016/j.jfluchem.2007.05.017
日期:2007.10
unambiguously by 1H and 19F NMR spectroscopy using a modified Mosher's method. From the optically active fluorinated allylic alcohols 1 corresponding esters 2 such as propionates, 3,3,3-trifluoropropionates and Boc-glycinates were synthesized. These compounds were rearranged to 2-substituted 4-fluoroalk-4-enecarboxylic acids 3 applying modified conditions of the [3,3]-sigmatropic Ireland-Claisen rearrangement
通过脂肪酶催化拆分末端烯烃合成的外消旋化合物,制备了一系列富含对映体的长链2-氟代烷基-1-en-3-醇1。就对映选择性而言,南极假丝酵母的脂肪酶显示是最有效的。氟化烯丙基醇1的酯交换作用优于相应乙酸盐2在磷酸盐缓冲液中的水解作用。脂肪酶在有机介质中催化烯丙基醇1的乙酰化,得到链长为C 10,C 16和C 18的(S)-(-)-3-乙酰氧基-2-氟代烷基-1-烯收率为68-89%,ee为92-96%,而其余(R)-(+)-2-氟代烷基-1-en-3-ols的收率为54-96%,ee为72-86%。通过比较测量和计算的CD光谱,并使用改进的Mosher法通过1 H和19 F NMR光谱明确地确定绝对构型。从光学活性的氟代烯丙基醇1,合成相应的酯2,例如丙酸酯,3,3,3-三氟丙酸酯和Boc-甘氨酸酸酯。这些化合物被重排为2-取代的4-氟烷-4-烯羧酸3运用[3,3] -sigmatropic