First Optically Active Heptalenes and their Absolute Configuration

Abstract

~~It is shown that dimethyl 7-isopropyl-5, IO-dimethylheptalene-1,2-dicarboxylate (1) and dimethyl 5,6,8,10-tetramethylheptalene-l,2-dicarboxylate (2) can be resolved via the corresponding mono-acids and with the aid of optically active primary or secondary amines such as I-phenylethylamine or ephedrine into the (-)-(P)-and (+)-(M)-enantiomeres, respectively. Characteristic for the (P)-chirality of the heptalene n-skeleton with C, or pseudo-C, symmetry are two (-)-CE's at the long wavelength region (450-300 nm) followed by at least one intense (+)-CE at wavelengths about or below 300 nm. The absolute configuration of the heptalenes was correlated with the well-established absolute configuration of (+)-(R)-and (-)-(S)-l -phenylethanol.

Formation of 3-Sulfonyl-Substituted Benzo[a]heptalene-2,4-diols from Heptalene-1,2-dicarboxylates and Lithiomethyl Phenyl Sulfones

“…The mixture of 1b and 1'b was directly subjected to photoisomerization with a high-pressure Hg lamp in MeCN as solvent (cf. [4]). After 3 h, a photostationary state was reached, consisting of 52% of 1b and 48% of 1'b, in good agreement with our former results in t-BuOMe as solvent [4].…”

“…[4]). After 3 h, a photostationary state was reached, consisting of 52% of 1b and 48% of 1'b, in good agreement with our former results in t-BuOMe as solvent [4]. Most of 1b could be removed from the mixture by crystallization from Et 2 O/hexane.…”

“…3 ) It might be that we have overlooked compounds of this type in our earlier investigations [1] due to their highly polar character. 4 ) The spectral data did not allow a clear-cut structural assignment of 9. 5 ) In the air, at room temperature, the crystals of 9 rapidly lose solvent molecules and disintegrate.…”

“…± The thermal reaction of 1,4,6,8-tetramethylazulene and a twofold excess of dimethyl acetylenedicarboxylate was performed in toluene at 1308 at a higher concentration than we had used in our earlier experiments [4], with the result that the yield of dimethyl 1,6,8,10-tetramethylheptalene-4,5-dicarboxylate (1b) could be improved to 47% (cf. [4] [5]). Heptalene 1b was accompanied by 4% of its DBS isomer 1'b and 27% of dimethyl 4,6,8-trimethylazulene-1,2-dicarboxylate (see Exper.…”

Tetramethylheptalenes and Their Tricarbonylchromium Complexes: Synthesis, Structures, and Thermal Rearrangements

“…It increases to 9.9 kcal/mol for heptalene-1,6-dicarbaldehyde [20], to 14.0 kcal/ mol for dimethyl heptalene-1,6-dicarboxylate [20], and to 26.7 kcal/mol for 1,2,5,6,8,10-hexamethylheptalene [2] [21]. Several peri-substituted heptalenes were isolated as individual DBS isomers, and their optical isomers were also resolved [2] [4] [22].…”