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A concise strategy for polymer‐supported regio‐oriented introduction of various building blocks onto glucopyranoside scaffold
Author(s) -
Liao Yuna,
Li ZhengMing,
Wong Henry N. C.
Publication year - 2001
Publication title -
chinese journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.28
H-Index - 41
eISSN - 1614-7065
pISSN - 1001-604X
DOI - 10.1002/cjoc.20010191120
Subject(s) - chemistry , reagent , steric effects , block (permutation group theory) , electrophilic substitution , molecule , substitution (logic) , scaffold , combinatorial chemistry , polymer , electrophile , stereochemistry , organic chemistry , catalysis , computer science , database , geometry , mathematics , programming language
A new strategy was devised to stereo‐specifically introduce various building blocks, mainly heterocycles such as pyrimidines and triazines onto a multi‐hydroxy molecule. A glucopyranoside was chosen as a target scaffold. Two polymer‐based protective reagents were jointly integrated in the implementation of the strategy. It was found that in the α‐ D ‐glucopyranoside, which has four free hydroxyl groups within the same molecule, its 4, 6‐di‐OH could be simultaneously protected by polystyryl boronic acid, which left the 2, 3‐di‐OH free for substitution. Due to the steric effects within the molecule, the 2‐OH is much more liabile to electrophilic substitution. Thus the first and the second building blocks could be introduced regioselectively onto the 2‐OH and the 3‐OH positions. After a facile deprotection, the 4, 6‐di‐OH were left free and by application of a second protecting reagent–‐polystyryltritylchloride onto 6‐OH, a third building block was introduced onto the 4‐OH position. After further deprotection, the fourth building block was later introduced onto the 6‐OH position. The new strategy was successfully applied in the combinatorial synthesis by application of the split‐mix technique. The respective eleven small libraries were obtained and confirmed by HPLC‐MS and NMR. Some preliminary results on chemical structure/herbicidal activity relationship were discussed.