5-N,4-O-carbonyl-7,8,9-tri-O-chloroacetyl-protected sialyl donor for the stereoselective synthesis of alpha-(2-->9)-tetrasialic acid.
An efficient stereoselective synthesis of alpha-(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 alpha-selective sialylation with various primary, secondary, and tertiary acceptors under in situ activation conditions (NIS/TfOH, -78 degrees C, acetonitrile/dichloromethane). The trans-fused oxazolidinone ring and O-chloroacetyl protecting groups were easily removed under mild reaction conditions to provide the fully deprotected alpha(2-->9)-tetrasialic acid.
Lin
Chang-Ching
CC
Department of Chemistry, National Tsing Hua University, 101, Sec. 2, Kuang Fu Rd, Hsinchu 30013, Taiwan.
Lin
Nai-Pin
NP
Sahabuddin
L Sk
LS
Reddy
Vijaya Raghava
VR
Huang
Li-De
LD
Hwang
Kuo Chu
KC
Lin
Chun-Cheng
CC