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Regioselective synthesis of 1,2- and 1,3-diaminothiacalix[4]arenes via nucleophilic aromatic substitution and their X-ray structures
| Content Provider | Semantic Scholar |
|---|---|
| Author | Katagiri, Hiroshi Tanaka, Shinya Ohkubo, Kazuya Akahira, Yuki Morohashi, Naoya Iki, Nobukiho Hattori, Tetsutaro Miyano, Sotaro |
| Copyright Year | 2014 |
| Abstract | Thiacalix[4]arenes bearing two amino groups instead of two hydroxy groups of p-tert-butylthiacalix[4]arene (2) at the distal 1,3- (5b) and proximal 1,2-positions (5c) are regioselectively synthesized via the nucleophilic aromatic substitution (SNAr) reaction of lithium benzylamide with tetra-O-methylsulfinylcalix[4]arenes 4(rctt) and 4(rcct), respectively. The SNAr reaction selectively proceeds at the benzene rings between two neighboring sulfinyl groups of a trans conformation. This is rationalized by the cooperative coordination of a methoxy group with a neighboring sulfinyl oxygen atom toward the metal ion to form a six-membered chelate, through which the amide ion attacks the aromatic nucleus. The N,O-hybrid thiacalixarenes 5b and 5c adopt cone conformations in their acetonitrile inclusion crystals. The distances between adjacent N and/or O atoms of their narrow-rim substituents indicate that the four substituents form a circular hydrogen-bond network but it is weaker than that of original thiacalixarene 2. Compound 5c also adopts a cone conformation in the guest-free crystal. This, combined with the fact that tetraaminated p-tert-butylthiacalix[4]arene 5a adopts a 1,3-alternate conformation in its guest-free crystal, indicates that the intramolecular O⋯N hydrogen bonds, not to mention the O⋯O hydrogen bond, in compound 5c play a crucial role in maintaining a cone conformation in the crystal. |
| Starting Page | 9608 |
| Ending Page | 9616 |
| Page Count | 9 |
| File Format | PDF HTM / HTML |
| DOI | 10.1039/C3RA47718E |
| Alternate Webpage(s) | http://www.rsc.org/suppdata/ra/c3/c3ra47718e/c3ra47718e.pdf |
| Alternate Webpage(s) | https://doi.org/10.1039/C3RA47718E |
| Volume Number | 4 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
