Synthesis of 1,4-, 2,4-, and 3,4-dimethylphenanthrenes: A novel deoxygenation of arene 1,4-endoxides with trimethylsilyl iodide
- Univ. of Michigan, Ann Arbor (USA)
A mild, efficient synthesis of the carcinogen 1,4-dimethylphenanthrene (2) and its bay-region methyl-bearing regioisomers 2,4-dimethyl- and 3,4-dimethylphenanthrenes (3 and 4) is described. The synthesis involves a generally applicable strategy that features a furan/dimethyl-1-naphthyne cycloaddition reaction followed by a convenient direct deoxygenation of the resulting enooxide with excess trimethylsilyl iodide generated in situ. The Friedel-Crafts cyclization of p-xylene with {gamma}-butyrolactone/AlCl{sub 3} or {gamma}-(2,5-dimethylphenyl)butyric acid via its trifluoromethanesulfonic anhydride derivative results in the formation of a mixture of 5,8-, 6,8-, and 5,7-dimethyl-1-tetralones (17, 20, and 21, respectively) through migration of aromatic methyl groups. The precursor to 6,8-dimethyl-1-naphthyne (10) was prepared from tetralone 20, isolable only as a 5:1 inseparable mixture with 17 from the direct Friedel-Crafts cyclization of p-xylene with {gamma}-butyrolactone, by {alpha}-dibromination with CuBr{sub 2}, dehydrobromination, and tosylation. The precursors to 5,8-dimethyl-1-naphthyne (9) and 7,8-dimethyl-1-naphthyne (11) were synthesized from the corresponding 1-naphthols 15 and 31, respectively. The synthesis of these naphthols involved cycloaddition between the corresponding dimethylated benzyne and furan followed by acid-catalyzed isomerization.
- OSTI ID:
- 7071043
- Journal Information:
- Journal of Organic Chemistry; (USA), Journal Name: Journal of Organic Chemistry; (USA) Vol. 54:24; ISSN JOCEA; ISSN 0022-3263
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400201* -- Chemical & Physicochemical Properties
550000 -- Biomedical Sciences
Basic Studies
59 BASIC BIOLOGICAL SCIENCES
AROMATICS
CHEMICAL REACTIONS
CONDENSED AROMATICS
DATA
DATA ANALYSIS
EXPERIMENTAL DATA
HYDROCARBONS
INFORMATION
MEASURING INSTRUMENTS
MEASURING METHODS
METHYLATION
NUMERICAL DATA
ORGANIC COMPOUNDS
PHENANTHRENE
POLYCYCLIC AROMATIC HYDROCARBONS
SYNTHESIS