Ultraviolet Absorption Spectra of Troponoids

Tropones and Tropolones

“…In tropolone the band is broadened and ranges from 225 to nearly 250 µ. In the spectrum of tropolone in cyclohexane, three peaks of approximately equal intensity can be clearly distinguished (9,65,96,436) in this region. The absorption of its methyl ether and its acetate are almost indistinguishable from that of the parent compound in this region, while that of the anion is shifted some 10 µ to a longer wave length.…”

“…Alkyl substitution has little effect except for a marked lowering in intensity of the higher-wave-length component of this band caused by alkyl groups in the 5-position (9,292). Halogens again cause a bathochromic shift (436). Additional hydroxyl groups have little effect, but carboxyl substituents cause a strong bathochromic shift, raising the maximum of, for example, stipitatic and (undissociated) puberulic acid to ca.…”

Carbon-carbon bond formation promoted by transition metal carbonyls. 18. New synthesis of troponoid compounds via the iron carbonyl promoted cyclocoupling between polybromo ketones and 1,3-dienes

“…Anal. (Ci3Hi7OBr) C, H. Hydrolysis of 15 (44.0 mg, 0.161 mmol) in a mixture of 48% HBr (4.5 mL), water (6.0 mL), and acetic acid (4.5 mL) was carried out at 130 °C for 10 h. Workup followed by preparative TLC (benzene) gave 17 (18.8 3,5-Dimethylbicyclo[5.1,0]octan-4-one (19). Gaseous diazomethane diluted with N2 was bubbled into a solution of 1 (388 mg, 2.80 mmol) and bis(7V-o:-phenylethylsalicylaldiminato)copper(II) (100 mg, 0.195 mmol) in a 1:1 mixture of benzene and hexane (5.0 mL) at -10 to 0 °C.…”

“…We developed a new, convenient route to the 2,7-dialkyl-4,5-homotropones starting from 4-cycloheptenones as illustrated in Scheme I. When gaseous diazo-methane diluted with nitrogen was introduced into a solution of 2,7-dimethyl-4-cycloheptenone (1) in a mixture of benzene and hexane at -5 to -10 °C in the presence of a catalytic amount of bis(A-a-phenylethylsalicylaldiminato)copper(II),23 19 was obtained in 90% yield. Bromination of 19 was done by addition of bromine into a mixture of 19 and sodium acetate in chloroform.…”

“…When gaseous diazo-methane diluted with nitrogen was introduced into a solution of 2,7-dimethyl-4-cycloheptenone (1) in a mixture of benzene and hexane at -5 to -10 °C in the presence of a catalytic amount of bis(A-a-phenylethylsalicylaldiminato)copper(II),23 19 was obtained in 90% yield. Bromination of 19 was done by addition of bromine into a mixture of 19 and sodium acetate in chloroform. The resulting dibromo derivatives were further subjected to dehydrobromination with a mixture of LiBr and LÍ2CO3 in DMF, giving the desired 4,5-homotropone 20.…”