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O ‐Alkylation of 3‐Formyl‐BINOL and Its Strong Effect on the Fluorescence Recognition of 1,3‐Diaminopropane
Author(s) -
Wang Ping,
Wang Li,
Yu Shanshan,
Wang Qin,
Pu Lin
Publication year - 2018
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201800715
Subject(s) - chemistry , alkylation , aldehyde , fluorescence , imine , intramolecular force , alkyl , proton nmr , diamine , medicinal chemistry , stereochemistry , organic chemistry , catalysis , physics , quantum mechanics
Systematic alkylation of the hydroxyl groups of 3‐formyl‐1,1′‐bi‐2‐naphthol (3‐formyl‐BINOL) has been conducted to generate four BINOL‐based aldehydes 2 – 5 . These compounds differ in the number and position of ethyl group at the two BINOL hydroxyl groups. Their fluorescence response toward various amines and diamines has been studied. It is found that when the hydroxyl group ortho to the aldehyde is alkylated, the resulting compounds 3 and 4 become highly selective molecular probes for 1,3‐diaminopropane (DAP), a biologically significant diamine, with large fluorescence enhancement. However, compound 2 that has no O ‐alkyl group and compound 5 that is only alkylated at the hydroxyl group distal to the aldehyde do not show large fluorescence enhancement. Through NMR and mass spectroscopic analyses, it is revealed that the imine products formed from the reactions of 2 and 5 with DAP can be stabilized by an intramolecular bonding interaction and give only weak fluorescence. Compounds 3 and 4 whose ortho ‐hydroxyl groups are alkylated react with DAP to form cyclic aminals to give greatly enhanced fluorescence.