202286-70-2Relevant academic research and scientific papers
Studies for a variable synthesis of colchicinoids: Construction of ring a on a heptalene moiety
Meyer, Markus,Abou-Hadeed, Khaled,Hansen, Hans-Juergen
, p. 2383 - 2397 (2000)
It is shown that heptalene-4,5-dicarboxylates 2, which react with lithiated methyl sulfones mainly in a Michael fashion at C(3) (cf. Scheme 2), so that the formation of 3-sulfonylbenzo[a]heptalene-2,4-diols 5 is repressed or completely suppressed, can be
From malaie anhydrides to substituted resorcinols
Abou-Hadeed, Khaled
, p. 760 - 762 (2007/10/03)
Symmetrically substituted maleic anhydrides react at-78 °C with lithiomethyl phenyl sulfoneto give the corresponding 4-hydroxy-4-(phenylsulfonylmethyl)-buteno-4-lactones, which, on treatment with Mel/ K2CO3 in acetone, are transformed into 5-methyl-5-phenylsulfonylcyclopent-2-ene-1,4-diones. These compounds rearrange in the presence of an excess of lithiomethyl phenyl sulfone at -78 °C and then butyllithium at -5 °C to ambient temperature into 4,5-disubstituted 6-methyl-2-phenylsulfonyl-resorcinols.
Formation of 3-sulfonyl-substituted benzo[a]heptalene-2,4-diols from heptalene-1,2-dicarboxylates and lithiomethyl phenyl sulfones
Lutz, Marc,Linden, Anthony,Abou-Hadeed, Khaled,Hansen, Hans-Juergen
, p. 372 - 388 (2007/10/03)
On treatment with 6 mol-equiv. of lithiomethyl phenyl sulfone at - 78°in THF, dimethyl 5,6,8,10-tetramethylheptalene-1,2-dicarboxylate (1'b) gives, after raising the temperature to - 10°and addition of 6 mol-equiv. of BuLi, followed by further warming to ambient temperature, the corresponding 3-(phenylsulfonyl)benzo[a]heptalene-2,4-diol 2b in yields up to 65% (cf. Scheme 6 and Table 2), in contrast to its doublebond-shifted (DBS) isomer 1b which gave 2b in a yield of only 6% [1]. The bisanion [9]2- of the cyclopenta[a]heptalen-l(1H)-one 9 (cf. Fig. 1), carrying a (phenylsulfonyl)methyl substituent at C(11b), seems to be a key intermediate on the reaction path to 2b, because 9 is transformed in high yield into 2b in the presence of 6 mol-equiv. of BuLi in the temperature range of - 10°to room temperature (cf. Scheme 7). Heptalenedicarboxylate 1'b was also transformed into benzo[a]heptalene-2,4-diols 2c-g by a number of lithiated methyl X-phenyl sulfones and BuLi (cf. Scheme 9 and Table 3).
A 'One-Pot' Anellation Method for the Transformation of Heptalene-4,5-dicarboxylates into Benzo[a]heptalenes
Abou-Hadeed, Khaled,Hansen, Hans-Juergen
, p. 2535 - 2564 (2007/10/03)
It has been found that dimethyl heptalene-4,5-dicarboxylates, when treated with 4 mol-equiv. of lithiated N,N-dialkylamino methyl sulfones or methyl phenyl sulfone, followed by 4 mol-equiv. of BuLi in THF in the temperature range of - 78 to 20°, give rise to the formation of 3-[(N,N-dialkylamino)sulfonyl]- or 3-(phenylsulfonyl)benzo[a]heptalene-2,4-diols (cf. Scheme 4, and Tables 2 and 3). Accompanying products are 2,4-bis{[(N,N-dialkylamino)sulfonyl]methyl}- or 2,4-bis[(phenylsulfonyl)methyl]-4,10a-dihydro-3H-heptaleno[1,10-bc]furan-3- carboxylates as mixtures of diastereoisomers (cf. Scheme 4, and Tables 2 and 3) which are the result of a Michael addition reaction of the lithiated methyl sulfones at C(3) of the heptalene-4,5-dicarboxylates, followed by (sulfonyl)methylation of the methoxycarbonyl group at C(5) and cyclization (cf. Scheme 5). It is assumed that the benzo[a]heptalene formation is due to (sulfonyl)methylation of both methoxycarbonyl groups of the heptalene4,5-dicarboxylates (cf. Schemes 6 and 8). The resulting bis-enolates 35 are deprotonated further. The thus formed tris-anions 36 can then cyclize to corresponding tris-anions 37 of cyclopenta[d]heptalenes which, after loss of N,N-dialkylamido sulfite or phenyl sulfinate, undergo a ring-enlargement reaction by 1,2-C migration finally leading to the observed benzo[a]heptalenes (cf. Schemes 8 and 9). The structures of the new product types have been finally established by X-ray crystal-structure analyses (cf. Figs. 1 and 2 as well as Exper. Part).
