Wiley InterScience Backfile Collection 1832-2000
Chemistry and Pharmacology
---The synthesis of new derivatives of 9,10-bis(1,3-dithiol-2-ylidene)-9,10-dihydroanthracene has been achieved by two different routes. Deprotonation of 8 using LDA in THF at -78 °C, followed by in situ quenching of the lithiated intermediate 9 with N,N-dimethylformamide, N-methyl isothiocyanate and methyl chloroformate gave aldehyde, thioamide and methyl ester derivatives 10-12, respectively. Sulfur insertion into the lithiated species 9 followed by reaction of the transient thiolate anion with benzoyl chloride gave the thioester derivative 13 which served as a convenient shelf-stable precursor of other mono-functionalised derivatives of 8. Debenzoylation of 13 and trapping of the transient thiolate anion with iodomethane and 6-bromohexan-1-ol yielded 14 and 15, respectively. Reaction of cation salt 17 with the anion of anthrone 18 gave compound 20, the thiolate anion of which reacted with 6-bromohexan-1-ol to afford the alcohol derivative 21. Subsequent reactions gave alcohol derivative 25 of the title system. The unexpected product 29 was obtained from reaction of 28 with triethyl phosphite. The X-ray crystal structures of compounds 12, 14, 28, and 29 are reported. The molecules adopt a saddle-like conformation; the bis(1,3-dithiole)benzoquinone system is U-shaped through an ‘accumulating bend’ comprising the boat conformation of the central (quinonoid) ring, folding of both 1,3-dithiole rings along S···S vectors, and out-of-plane tilting of the exocyclic C=C bonds, all in the same (inward) direction.
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