5-<i>N</i>,4-<i>O</i>-Carbonyl-7,8,9-tri-<i>O</i>-chloroacetyl-Protected Sialyl Donor for the Stereoselective Synthesis of α-(2→9)-Tetrasialic Acid
作者:Chang-Ching Lin、Nai-Pin Lin、L. Sk Sahabuddin、Vijaya Raghava Reddy、Li-De Huang、Kuo Chu Hwang、Chun-Cheng Lin
DOI:10.1021/jo100824s
日期:2010.8.6
An efficient stereoselective synthesis of α-(2→9)-tetrasialic acid was achieved using tri-O-chloroacetyl-derivatized sialyl donor and a triol sialyl acceptor. Both the acceptor and the donor were also protected with a cyclic 5-N-4-O-carbonyl protecting group. The donor is highly reactive and enabled α-selective sialylation with various primary, secondary, and tertiary acceptors under in situ activation
使用三-O-氯乙酰基衍生的唾液酸供体和三醇唾液酸受体实现了α-(2→9)-四唾液酸的有效立体选择性合成。受体和供体也都被环状5- N -4- O-羰基保护基保护。供体在原位活化条件(NIS / TfOH,-78°C,乙腈/二氯甲烷)下具有高反应活性,并且能够与各种伯,仲和叔受体进行α-选择性唾液酸化。在温和的反应条件下,容易除去反式稠合的恶唑烷酮环和O-氯乙酰基保护基,以提供完全脱保护的α(2→9)-四唾液酸。