The Synthesis of 1-Phenylazulene and 2-Phenylazulene from the Troponoid Compound

Nozoe, Tetsuo; Takase, Kahei; Fukuda, S.

doi:10.1246/bcsj.44.2210

Cited by 23 publications

(25 citation statements)

References 6 publications

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“…N 2 . 2,4,3,4,5, were synthesized according to [2]. The 4-NO 2 and 4-MeO derivatives of 3-phenylprop-2-ynoic acid were prepared according to [21].…”

Section: Experimental Partmentioning

confidence: 99%

“…According to [6], acid 5a was converted, via its chloride 9c, to 3b; yield 81%. (3,4,5)); 2.24 (s, MeÀC (2,6)). 13 16,H 6.89;found: C 81.93,H 6.92.…”

Section: Experimental Partmentioning

confidence: 99%

“…1.2.4.1. 2,3,4,5,. A 500-ml flask was charged with toluene (30 ml), CH 2 Cl 2 (40 ml), and 2,3,4,5,6-pentabromophenol (36.88 g, 75.5 mmol).…”

Section: Experimental Partmentioning

confidence: 99%

“…1.2.7. 2,4, . From 5'c (0.058 g, 0.545 mmol) and 6a (0.110 g, 0.545 mmol), 3h (0.055 g, 50%) was obtained as a glassy mass, according to Procedure B.…”

Section: Experimental Partmentioning

confidence: 99%

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Unexpected Thermal Transformation of Aryl 3-Arylprop-2-ynoates: Formation of 3-(Diarylmethylidene)-2,3-dihydrofuran-2-ones

Lellek

Hansen

2001

HCA

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Dedicated to Conrad Hans Eugster on the occasion of his 80th birthday A number of aryl 3-arylprop-2-ynoates 3 has been prepared (cf. Table 1 and Schemes 3 ± 5). In contrast to aryl prop-2-ynoates and but-2-ynoates, 3-arylprop-2-ynoates 3 (with the exception of 3b) do not undergo, by flash vacuum pyrolysis (FVP), rearrangement to corresponding cyclohepta[b]furan-2(2H)-ones 2 (cf. Schemes 1 and 2). On melting, however, or in solution at temperatures > 1508, the compounds 3 are converted stereospecifically to the dimers 3-[(Z)-diarylmethylidene]-2,3-dihydrofuran-2-ones (Z)-11 and the cyclic anhydrides 12 of 1,4-diarylnaphthalene-2,3-dicarboxylic acids, which also represent dimers of 3, formed by loss of one molecule of the corresponding phenol from the aryloxy part (cf. Scheme 6). Small amounts of diaryl naphthalene-2,3-dicarboxylates 13 accompanied the product types (Z)-11 and 12, when the thermal transformation of 3 was performed in the molten state or at high concentration of 3 in solution (cf. Tables 2 and 4). The structure of the dihydrofuranone (Z)-11c was established by an X-ray crystal-structure analysis (Fig. 1). The structures of the dihydrofuranones 11 and the cyclic anhydrides 12 indicate that the 3-arylprop-2-ynoates 3, on heating, must undergo an aryl O 3 C(3) migration leading to a reactive intermediate, which attacks a second molecule of 3, finally under formation of (Z)-11 or 12. Formation of the diaryl dicarboxylates 13, on the other hand, are the result of the well-known thermal Diels-Alder-type dimerization of 3 without rearrangement (cf. Scheme 7). At low concentration of 3 in decalin, the decrease of 3 follows up to ca. 20% conversion first-order kinetics (cf . Table 5), which is in agreement with a monomolecular rearrangement of 3. Moreover, heating the highly reactive 2,4,6-trimethylphenyl 3-(4-nitrophenyl)prop-2-ynonate (3f) in the presence of a twofold molar amount of the much less reactive phenyl 3-(4-nitrophenyl)prop-2-ynonate (3g) led, beside (Z)-11f, to the cross products (Z)-11fg, and, due to subsequent thermal isomerization, (E)-11fg (cf. Scheme 10), the structures of which indicated that they were composed, as expected, of rearranged 3f and structurally unaltered 3g. Finally, thermal transposition of [ 17 O]-3i with the 17 O-label at the aryloxy group gave (Z)-and (E)-[ 17 O 2 ]-11i with the 17 O-label of rearranged [ 17 O]-3i specifically at the oxo group of the two isomeric dihydrofuranones (cf. Scheme 8), indicating a highly ordered cyclic transition state of the aryl O 3 C(3) migration (cf. Scheme 9).

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“…N 2 . 2,4,3,4,5, were synthesized according to [2]. The 4-NO 2 and 4-MeO derivatives of 3-phenylprop-2-ynoic acid were prepared according to [21].…”

Section: Experimental Partmentioning

confidence: 99%

“…According to [6], acid 5a was converted, via its chloride 9c, to 3b; yield 81%. (3,4,5)); 2.24 (s, MeÀC (2,6)). 13 16,H 6.89;found: C 81.93,H 6.92.…”

Section: Experimental Partmentioning

confidence: 99%

“…1.2.4.1. 2,3,4,5,. A 500-ml flask was charged with toluene (30 ml), CH 2 Cl 2 (40 ml), and 2,3,4,5,6-pentabromophenol (36.88 g, 75.5 mmol).…”

Section: Experimental Partmentioning

confidence: 99%

“…1.2.7. 2,4, . From 5'c (0.058 g, 0.545 mmol) and 6a (0.110 g, 0.545 mmol), 3h (0.055 g, 50%) was obtained as a glassy mass, according to Procedure B.…”

Section: Experimental Partmentioning

confidence: 99%

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Unexpected Thermal Transformation of Aryl 3-Arylprop-2-ynoates: Formation of 3-(Diarylmethylidene)-2,3-dihydrofuran-2-ones

Lellek

Hansen

2001

HCA

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“…The general trend is that all bands are shifted to lower wave numbers with the increase of the number of alkyl substituents at the seven-membered ring, whereby the unsubstituted 3a and its pentamethyl derivative As a rule, all furanones show at least two vibrational bands in the n Ä (CO) region that may appear as two distinct bands as in the case of 3f or the previously mentioned 3-phenylfuranone derivative. Already, Nozoe et al pointed out [57] that this bandsplitting resembles those for n Ä (CO) of a,b-unsaturated five-ring lactones [58]. However, this splitting has been ascribed to a Fermi resonance coupling with a vibration involving the a-CÀH bond, because a-substituted a,b-unsaturated g-lactones do not exhibit this splitting.…”

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confidence: 99%

Synthesis of Polyalkylphenyl Prop-2-ynoates and Their Flash Vacuum Pyrolysis to Polyalkylcyclohepta[b]furan-2(2H)-ones

Nagel

Hansen

2000

HCA

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A new method for the smooth and highly efficient preparation of polyalkylated aryl propiolates has been developed. It is based on the formation of the corresponding aryl carbonochloridates (cf. Scheme 1 and Table 1) that react with sodium (or lithium) propiolate in THF at 25 – 65°, with intermediate generation of the mixed anhydrides of the arylcarbonic acids and prop‐2‐ynoic acid, which then decompose almost quantitatively into CO2 and the aryl propiolates (cf. Scheme 11). This procedure is superior to the transformation of propynoic acid into its difficult‐to‐handle acid chloride, which is then reacted with sodium (or lithium) arenolates. A number of the polyalkylated aryl propiolates were subjected to flash vacuum pyrolysis (FVP) at 600 – 650° and 10−2 Torr which led to the formation of the corresponding cyclohepta[b]furan‐2(2H)‐ones in average yields of 25 – 45% (cf. Scheme 14). It has further been found in pilot experiments that the polyalkylated cyclohepta[b]furan‐2(2H)‐ones react with 1‐(pyrrolidin‐1‐yl)cyclohexene in toluene at 120 – 130° to yield the corresponding 1,2,3,4‐tetrahydrobenz[a]azulenes, which become, with the growing number of Me groups at the seven‐membered ring, more and more sensitive to oxidative destruction by air (cf. Scheme 15).

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Palladium‐Catalyzed Direct Arylation of Azulene Based on Regioselective C−H Bond Activation

et al. 2016

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An efficient synthesis of arylazulenes involving minimal steps was developed. The combination of Pd(OAc) 2 / XPhos as ac atalysta nd pivalica cid as an additive was key for the direct arylation of CÀHb onds, and the reactionp roceeded preferentially at the 1-and 3-positions of azulene, without heteroatom-containing directing groups. Compared with the traditional cross-coupling protocol, the arylation method described here requires fewer steps and uses commerciallya vailables ynthetic blocks. The degree of conjugation and the optical properties of the resulting azulenec onjugates can be adjusted by simple protonation, whicha llows the current method to be an efficient strategy for exploiting novel azulene-based functional materials.[a] Dr.

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The Synthesis of 1-Phenylazulene and 2-Phenylazulene from the Troponoid Compound

Cited by 23 publications

References 6 publications

Unexpected Thermal Transformation of Aryl 3-Arylprop-2-ynoates: Formation of 3-(Diarylmethylidene)-2,3-dihydrofuran-2-ones

Unexpected Thermal Transformation of Aryl 3-Arylprop-2-ynoates: Formation of 3-(Diarylmethylidene)-2,3-dihydrofuran-2-ones

Synthesis of Polyalkylphenyl Prop-2-ynoates and Their Flash Vacuum Pyrolysis to Polyalkylcyclohepta[b]furan-2(2H)-ones

Palladium‐Catalyzed Direct Arylation of Azulene Based on Regioselective C−H Bond Activation

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