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Synthetic Approach Towards Hexaprismane. A Novel Entry to Homosecohexaprismane Skeleton by Cage Enlargement
Author(s) -
Chou TehChang,
Lin GerngHorng,
Yeh YuLin,
Lin KuanJiuh
Publication year - 1997
Publication title -
journal of the chinese chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.329
H-Index - 45
eISSN - 2192-6549
pISSN - 0009-4536
DOI - 10.1002/jccs.199700073
Subject(s) - chemistry , maleic anhydride , adduct , azine , acetic anhydride , benzene , keto–enol tautomerism , medicinal chemistry , diol , acetic acid , catalysis , organic chemistry , stereochemistry , copolymer , polymer
A series of caged 1,4‐diols, 26, 29a/29b, 31 , were synthesized from the Diels‐Alder cycloadduct 21 of 1,2,3,4‐tetrachloro‐5,5‐dimethoxycyclopentadiene and 1,4‐benzoquinone. Reduction of enedione 21 with aqueous TiCl 3 , followed by base‐catalyzed enolization in the presence of acetic anhydride, gave diene 23b , which reacted with maleic anhydride and 1,4‐benzoquinone to produce the corresponding [4+2] cycloadducts 24b and 27 , respectively. The adduct 24b was converted to birdcaged 1,4‐diol 26 by photocyclization followed by decarboxylative olefination of resulted caged anhydride 25b . The adduct 27 was photocyclized to cage compound 28 , which was aromatized to dihydroquinone 29a by acid‐catalyzed enolization, or benzo‐annulated compound 31 by reduction and dehydration. The birdcaged 1,4‐diols 26 and 31 underwent fragmentation induced by (diacetoxyiodo)benzene to give enediones 38/39 and 41/42 , respectively. Photocyclization of 38 and 39 produced the corresponding caged compounds 43 and 44 , respectively, possessing homosecohexaprismane skeletons. The corresponding monohydrate 43a of 43 was structurally characterized by single‐crystal X‐ray diffraction.