1,4-Benzoquinones with Styryl Substituents

Abstract

2-Styryl-1,4-benzoquinone (1) and compounds 2 and 3 containing 1 as a substructure all proved to be highly reactive towards thermal or photochemical [4π + 2π] cyclodimerization reactions. Chemo-, regio-and stereoselective processes lead to dimers (compounds 1−10), which can undergo secondary reactions consisting of the addition of nucleophiles combined with a twofold keto-enol tautomerism (10 Ǟ 12). An alternative process is dehydrogenation/oxidation followed by an intramolecular [4π + 2π] cycloaddition (10 Ǟ 11).

Photochemical stability of dicyano‐substituted poly(phenylenevinylenes) with different side chains

“…1 H NMR (400 MHz, CDCl 3 , δ, ppm): 0.89 (t, J = 6.38 Hz, 6H), 1.25–1.45 (m, 20H), 1.63 (quint, J = 7.55, 4H), 2.66 (t, J = 9.06 Hz, 4H), 4.49 (s, 4H), 7.14 (s, 2H). The spectrum is consistent with that of 2,5‐bis(bromomethyl)−1,4‐bis(hexyl)benzene found in literature …”

“…The synthetic steps for C8‐diCN‐PPV and RO‐diCN‐PPV are shown in Scheme . The synthesis of 2 used a procedure similar to that used by Brehm et al for the synthesis of 1,4‐dihexyl‐2,5‐bis(bromomethyl)benzene . Initially, following this procedure yielded very little product, due to the formation of a biphasic solution.…”

Photochemical stability of dicyano‐substituted poly(phenylenevinylenes) with different side chains

“…1 H NMR (400 MHz, CDCl 3 , δ, ppm): 0.89 (t, J = 6.38 Hz, 6H), 1.25–1.45 (m, 20H), 1.63 (quint, J = 7.55, 4H), 2.66 (t, J = 9.06 Hz, 4H), 4.49 (s, 4H), 7.14 (s, 2H). The spectrum is consistent with that of 2,5‐bis(bromomethyl)−1,4‐bis(hexyl)benzene found in literature …”

“…The synthetic steps for C8‐diCN‐PPV and RO‐diCN‐PPV are shown in Scheme . The synthesis of 2 used a procedure similar to that used by Brehm et al for the synthesis of 1,4‐dihexyl‐2,5‐bis(bromomethyl)benzene . Initially, following this procedure yielded very little product, due to the formation of a biphasic solution.…”

One‐Pot Synthesis to Quinone‐Based Diaza[3.3]cyclophanes

“…[14,16] Both bromomethyl groups were installed by a Blanctype reaction with paraformaldehyde and hydrogen bromide in acetic acid. [17] In the final step, quinone 1 was re-established by nitric acid (Scheme 2). In general, all steps are easy to conduct and scalable.…”

Synthesis, Antifungal Activity, and Structure−Activity Relationships of Coruscanone A Analogues

“…Dehydration and deprotection of 58 using mineral acid yielded stilbene 59 , which was oxidized by DDQ to furnish 60 (Scheme ). In view of the limited number of available methods for the synthesis of styrylbenzoquinones, it is worthwhile mentioning that direct coupling of phenylacetaldehyde with diortho-oxygenated benzenes, followed by oxidation, is a facile method for preparation of 2-hydroxy (or methoxy)-3-styrylbenzoquinone derivatives.

2 Synthesis of Benzoquinone 60 a a Reagents and conditions: (a) MeOCH 2 Cl/NaH, THF, 0 °C, 24 h, 75%; (b) C 5 H 5 NHBr 3 /MeOH/NaHCO 3 , room temp, 25 min, 89%; (c) (i) MeLi/THF, −78 °C, 1 h; (ii) MeI, −78 °C, 1 h, 90%; (d) (i) BuLi/THF, −78 °C, 1 h, then warm to 0 °C, 5 h, room temp, 3 h; (ii) PhCH 2 CHO, 0 °C, 0.5 h; 66%.

…”

Photochemical stability of dicyano‐substituted poly(phenylenevinylenes) with different side chains

“…1 H NMR (400 MHz, CDCl 3 , δ, ppm): 0.89 (t, J = 6.38 Hz, 6H), 1.25–1.45 (m, 20H), 1.63 (quint, J = 7.55, 4H), 2.66 (t, J = 9.06 Hz, 4H), 4.49 (s, 4H), 7.14 (s, 2H). The spectrum is consistent with that of 2,5‐bis(bromomethyl)−1,4‐bis(hexyl)benzene found in literature …”

“…The synthetic steps for C8‐diCN‐PPV and RO‐diCN‐PPV are shown in Scheme . The synthesis of 2 used a procedure similar to that used by Brehm et al for the synthesis of 1,4‐dihexyl‐2,5‐bis(bromomethyl)benzene . Initially, following this procedure yielded very little product, due to the formation of a biphasic solution.…”

One‐Pot Synthesis to Quinone‐Based Diaza[3.3]cyclophanes

“…[14,16] Both bromomethyl groups were installed by a Blanctype reaction with paraformaldehyde and hydrogen bromide in acetic acid. [17] In the final step, quinone 1 was re-established by nitric acid (Scheme 2). In general, all steps are easy to conduct and scalable.…”

Synthesis, Antifungal Activity, and Structure−Activity Relationships of Coruscanone A Analogues

“…Dehydration and deprotection of 58 using mineral acid yielded stilbene 59 , which was oxidized by DDQ to furnish 60 (Scheme ). In view of the limited number of available methods for the synthesis of styrylbenzoquinones, it is worthwhile mentioning that direct coupling of phenylacetaldehyde with diortho-oxygenated benzenes, followed by oxidation, is a facile method for preparation of 2-hydroxy (or methoxy)-3-styrylbenzoquinone derivatives.

2 Synthesis of Benzoquinone 60 a a Reagents and conditions: (a) MeOCH 2 Cl/NaH, THF, 0 °C, 24 h, 75%; (b) C 5 H 5 NHBr 3 /MeOH/NaHCO 3 , room temp, 25 min, 89%; (c) (i) MeLi/THF, −78 °C, 1 h; (ii) MeI, −78 °C, 1 h, 90%; (d) (i) BuLi/THF, −78 °C, 1 h, then warm to 0 °C, 5 h, room temp, 3 h; (ii) PhCH 2 CHO, 0 °C, 0.5 h; 66%.

…”

Photochemical stability of dicyano‐substituted poly(phenylenevinylenes) with different side chains

“…1 H NMR (400 MHz, CDCl 3 , δ, ppm): 0.89 (t, J = 6.38 Hz, 6H), 1.25–1.45 (m, 20H), 1.63 (quint, J = 7.55, 4H), 2.66 (t, J = 9.06 Hz, 4H), 4.49 (s, 4H), 7.14 (s, 2H). The spectrum is consistent with that of 2,5‐bis(bromomethyl)−1,4‐bis(hexyl)benzene found in literature …”

“…The synthetic steps for C8‐diCN‐PPV and RO‐diCN‐PPV are shown in Scheme . The synthesis of 2 used a procedure similar to that used by Brehm et al for the synthesis of 1,4‐dihexyl‐2,5‐bis(bromomethyl)benzene . Initially, following this procedure yielded very little product, due to the formation of a biphasic solution.…”

One‐Pot Synthesis to Quinone‐Based Diaza[3.3]cyclophanes

“…[14,16] Both bromomethyl groups were installed by a Blanctype reaction with paraformaldehyde and hydrogen bromide in acetic acid. [17] In the final step, quinone 1 was re-established by nitric acid (Scheme 2). In general, all steps are easy to conduct and scalable.…”

Synthesis, Antifungal Activity, and Structure−Activity Relationships of Coruscanone A Analogues

“…Dehydration and deprotection of 58 using mineral acid yielded stilbene 59 , which was oxidized by DDQ to furnish 60 (Scheme ). In view of the limited number of available methods for the synthesis of styrylbenzoquinones, it is worthwhile mentioning that direct coupling of phenylacetaldehyde with diortho-oxygenated benzenes, followed by oxidation, is a facile method for preparation of 2-hydroxy (or methoxy)-3-styrylbenzoquinone derivatives.

2 Synthesis of Benzoquinone 60 a a Reagents and conditions: (a) MeOCH 2 Cl/NaH, THF, 0 °C, 24 h, 75%; (b) C 5 H 5 NHBr 3 /MeOH/NaHCO 3 , room temp, 25 min, 89%; (c) (i) MeLi/THF, −78 °C, 1 h; (ii) MeI, −78 °C, 1 h, 90%; (d) (i) BuLi/THF, −78 °C, 1 h, then warm to 0 °C, 5 h, room temp, 3 h; (ii) PhCH 2 CHO, 0 °C, 0.5 h; 66%.

…”