Premium
Medium‐Sized Cyclophanes, 20. Synthesis and Conformational Studies of syn ‐ and anti ‐Dihydroxy[ n .2]metacyclophanes
Author(s) -
Yamato Takehiko,
Matsumoto JunIchi,
Tokuhisa Kiwamu,
Kajihara Masami,
Suehiro Kazuaki,
Tashiro Masashi
Publication year - 1992
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19921251116
Subject(s) - chemistry , cyclophane , stereochemistry , dichloromethane , nmr spectra database , demethylation , benzene , medicinal chemistry , crystal structure , crystallography , spectral line , organic chemistry , biochemistry , physics , gene expression , astronomy , solvent , dna methylation , gene
syn ‐ and anti ‐Dimethoxy[ n .2]metacyclophanes 9 are obtained by pyrolysis of the corresponding anti ‐sulfones 8 , which are prepared by the reaction of 1, n ‐bis[3‐(chloromethyl)‐2‐methoxyphenyl]alkanes 6 with Na 2 S in ethanol under the high dilution conditions, followed by the oxidation of the obtained thiametacyclophanes 7 with m ‐chloroperbenzoic acid. Demethylation of anti ‐dimethoxy[ n .2]metacyclophanes anti ‐9 with BBr 3 in dichloromethane affords the corresponding anti ‐dihydroxy[ n .2]metacyclophanes anti ‐ 10 . On the other hand, demethylation of syn ‐dimethoxy[3.2]‐ syn ‐ 9b and ‐[4.2]meta‐cyclophane syn‐ 9c gives syn ‐dihydroxy[ n .2]metacyclophanes syn ‐ 10b, c , but syn ‐dimethoxy[5.2]‐ syn ‐ 9d and ‐[6.2]metacyclophane syn ‐ 9e are converted into the corresponding anti ‐dihydroxy[ n .2]metacyclophanes anti ‐ 10d, e . AlCl 3 · CH 3 NO 2 ‐catalyzed de‐ tert ‐butylation of tert ‐butyl‐ syn ‐ and ‐ anti ‐dihydroxy[3.2]‐ and ‐[4.2]metacyclophanes syn/anti ‐ 10b, c has been carried out in benzene to give the desired metacyclophanes anti ‐ 11a–c and syn ‐ 11c except syn ‐dihydroxy‐[3.2]metacyclophane syn ‐ 11b which is converted into 8,17‐epoxy[3.2]metacyclophane 13 . The assignment of syn and anti conformations has been confirmed by 1 H‐NMR analyses and X‐ray diffraction studies. The dynamics of the ring inversion and UV spectra are also discussed.