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Synthesis and Properties of syn ‐[2.2](1,6)‐ and (4,6)Azulenophanes and Macrocyclic Azulenophanes
Author(s) -
Chen ShuLing,
Klein Roland,
Hafner Klaus
Publication year - 1998
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/(sici)1099-0690(199803)1998:3<423::aid-ejoc423>3.0.co;2-e
Subject(s) - chemistry , protonation , formylation , deprotonation , azulene , medicinal chemistry , intramolecular force , oxidative coupling of methane , yield (engineering) , regioselectivity , annulene , stereochemistry , photochemistry , organic chemistry , ion , materials science , methane , metallurgy , catalysis
A regioselective synthesis of syn ‐[2.2](1,6)azulenophane ( 9 ) and syn ‐[2.2](4,6)azulenophane ( 12 ) is described. Azulenophane 9 is prepared by deprotonation of 1,2‐bis(6‐methylazulen‐1‐yl)ethane ( 5 ), followed by oxidative coupling of the initially formed dilithium salt 8 with iodine under high‐dilution conditions in 17% yield, along with the macrocyclic [2.2.2.2](1,6)azulenophane ( 10 ) (3%), and [2.2.2.2.2.2](1,6)azulenophane ( 11 ) (1.5%). The azulenophane 12 and the macrocyclic [2.2.2.2](4,6)azulenophane ( 13 ) are obtained by coupling of the dianion of 1,2‐bis(4‐methylazulen‐6‐yl)ethane ( 14 ). The structural assignments of the title compounds are based on their spectral data. Protonation of 9 furnishes the mono‐ and dications 24 and 25 , respectively, of which the first exhibits a charge‐transfer band in its electronic spectrum, indicating a transannular interaction between the protonated and unprotonated azulene units. Protonation of 12 yields the mono‐ and dications 26 and 27 , respectively. In contrast to 24 , no new band due to an intramolecular transannular charge‐transfer interaction is observed in the electronic spectrum of 26 , and this is due to an insufficient overlap between the protonated and unprotonated azulene decks in 26 . Vilsmeier formylation of 9 with 1.5 mol equivalents of phosphoryl chloride in DMF at room temp. yields 3‐formyl‐ syn ‐[2.2](1,6)azulenophane ( 28 ) in 15% yield. Under the same reaction conditions a double formylation of 9 with 3 mol equivalents of phosphoryl chloride leads to 3,3′‐diformyl‐ syn ‐[2.2](1,6)azulenophane ( 29 ) in 42% yield. The aminomethylation of 9 with paraformaldehyde and N, N, N′, N′ ‐tetramethyldiaminomethane in the presence of acetic acid furnishes the Mannich bases 3‐ N, N ‐dimethylaminomethyl‐ syn ‐[2.2](1,6)azulenophane ( 30 ) and 3,3′‐bis( N, N ‐dimethylaminomethyl)‐ syn ‐[2.2](1,6)azulenophane ( 31 ) in 40% and 46% yields, respectively.