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Synthesis of a New Potential Tridentate Anthracene Ligand Bearing Deprotectable Methoxymethoxy (OMOM) Group at 1,8‐Positions: Attempt To Synthesize Anionic Hypervalent Carbon Compounds
Author(s) -
Yamashita Makoto,
Mita Yukari,
Yamamoto Yohsuke,
Akiba Kinya
Publication year - 2003
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200204354
Subject(s) - chemistry , medicinal chemistry , deprotonation , ligand (biochemistry) , crown ether , adduct , electrophile , hypervalent molecule , ether , lithium (medication) , anthracene , polymer chemistry , stereochemistry , photochemistry , reagent , organic chemistry , ion , medicine , biochemistry , receptor , endocrinology , catalysis
A novel potential tridentate ligand bearing deprotectable coordinating atoms, 1,8‐bis(methoxymethoxy)‐9‐bromoanthracene ( 15 ), was synthesized. The key steps are as follows: 1) stepwise mono‐oxygenation from 1,8‐dibromo‐9‐methoxyanthracene by use of electrophilic oxaziridine and gaseous dioxygen, and 2) selective reduction of the methoxy group by LDBB (lithium di‐ tert ‐butylbiphenylide) followed by treatment with BrCF 2 CF 2 Br. The corresponding 1,8‐bis(methoxymethoxy)‐9‐lithio‐anthracene ( 14 ), which should be a useful versatile trianion equivalent, could be generated by treatment of the bromide with one equivalent of n BuLi. The lithioanthracene reacted with hexafluoroacetone to give the deprotected ether 17 together with the adduct alcohol 16 . The ether could easily be deprotected to give 1,2‐dihydro‐1,1‐bis(trifluoromethyl)‐2‐oxa‐9‐hydroxyanthrylene ( 8 ), which was deprotonated with KH in the presence of [18]crown‐6 to give the corresponding anion ( 9 ‐K([18]crown‐6)). The X‐ray structure and NMR spectra of 9 ‐K([18]crown‐6) showed that it has an unsymmetrical structure probably due to the interaction between the oxygen atom of the phenoxide and the potassium cation surrounded by the crown ether.