59043-48-0Relevant academic research and scientific papers
Dibenzothiepins, phthalans and phthalides from 4-heterosubstituted dibenzothiins
Yus, Miguel,Foubelo, Francisco,Ferrández, José V.
, p. 2083 - 2092 (2003)
The lithiation of 4-heterosubstituted dibenzothiins 1 (phenoxathiin, phenothiazine and thianthrene) with lithium and a catalytic amount of 4,4′-di-tert-butylbiphenyl (DTBB, 7.5% molar) in THF at temperatures ranging from -90 to -78°C gives the corresponding functionalised organolithium intermediate I, which by reaction with different electrophiles [H2O, D2O, ButCHO, PhCHO, Ph(CH2)2CHO, Me2CO, Et2CO, (CH2)5CO, (CH2)7CO] at the same temperature, followed by hydrolysis, gives the expected functionalised thiols 2. Cyclisation of some thiols 2 under acidic conditions leads to the corresponding seven-membered dibenzo heterocycles 5. In the case of thianthrene 1c, after addition of a carbonyl compound as the first electrophile [MeCHO, ButCHO, Me2CO, Et2CO, (CH2)5CO], the corresponding intermediate II can be lithiated again and react with a second electrophile. Diols 3 are obtained after hydrolysis when a carbonyl compound [ButCHO, PhCHO, Ph(CH2)2CHO, Me2CO, Et2CO, (CH2)5CO] is used as the second electrophile. Acidic cyclisation of diols 3 gives substituted phthalans 6 in almost quantitative yields. Finally, in the case of using carbon dioxide as the second electrophile, phthalides 4 are obtained after acidic hydrolysis.
Thianthrene as a source of the 1,2-benzene dianion
Yus, Miguel,Foubelo, Francisco,Ferrández, José V.
, p. 7205 - 7207 (2007/10/03)
The lithiation of thianthrene 1 with lithium and a catalytic amount of 4,4′-di-tert-butylbiphenyl (DTBB, 4% molar) in THF at -90°C, followed by reaction with a carbonyl compound [ButCHO, Me2CO, Et2CO, (CH2)5CO] at the same temperature, gives an intermediate, which was lithitated again and reacted with a second carbonyl compound [ButCHO, PhCHO, Ph(CH2)2CHO, Me2CO, Et2CO, (CH2)5CO] to give, after the final hydrolysis, the expected diols 2. Compounds 2 are easily cyclised under acidic conditions (85% H3PO4) to yield the expected phthalans in almost quantitative yields. Finally, when after the reaction with the first carbonyl compound (PhCHO, Me2CO), carbon dioxide was used as the second electrophile, the expected substituted phthalides 3 were obtained after acidic work-up.
