The photocyclization of anils to phenanthridines

Mallory, Frank B.; Wood, Clelia S.

doi:10.1016/s0040-4039(00)90222-3

Cited by 23 publications

(6 citation statements)

References 15 publications

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“…N -phenylbenzophenone imine ( 1 ) was selected as a model compound for optimization of the photocyclization reaction conditions. Irradiation of 322 mg of this imine for 67 h in 250 mL of cyclohexane using a 400-watt mercury lamp provided 6-phenylphenanthridine ( 2 ) in 46% isolated yield [ 28 ]. According to the literature [ 31 , 32 , 33 ], the reaction on similar substrates can be accelerated via protonation of starting imine by addition of acid.…”

Section: Resultsmentioning

confidence: 99%

“…This failure was originally explained by an extremely low concentration of Z -isomer in photochemical equilibrium at room temperature. A two percent yield was achieved at −10 °C, where the rate of the thermal E/Z isomerization is decreased [ 28 ]. Another factor that disfavors the photocyclization is the presence of an electron lone pair on nitrogen.…”

Section: Introductionmentioning

confidence: 99%

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Oxidative Photocyclization of Aromatic Schiff Bases in Synthesis of Phenanthridines and Other Aza-PAHs

Kos

Žádný

Storch

et al. 2020

IJMS

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The oxidative photocyclization of aromatic Schiff bases was investigated as a potential method for synthesis of phenanthridine derivatives, biologically active compounds with medical applications. Although it is possible to prepare the desired phenanthridines using such an approach, the reaction has to be performed in the presence of acid and TEMPO to increase reaction rate and yield. The reaction kinetics was studied on a series of substituted imines covering the range from electron-withdrawing to electron-donating substituents. It was found that imines with electron-withdrawing substituents react one order of magnitude faster than imines bearing electron-donating groups. The 1H NMR monitoring of the reaction course showed that a significant part of the Z isomer in the reaction is transformed into E isomer which is more prone to photocyclization. The portion of the Z isomer transformed showed a linear correlation to the Hammett substituent constants. The reaction scope was expanded towards synthesis of larger aromatic systems, namely to the synthesis of strained aromatic systems, e.g., helicenes. In this respect, it was found that the scope of oxidative photocyclization of aromatic imines is limited to the formation of no more than five ortho-fused aromatic rings.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Oxidative Photocyclization of Aromatic Schiff Bases in Synthesis of Phenanthridines and Other Aza-PAHs

Kos

Žádný

Storch

et al. 2020

IJMS

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“…1 This hypothesis can be tested with the help of imine 3 in which the cis configuration is built in by molecular design. 21 However, no product (4) could be detected after 24 hours of exposure time. Scheme 2.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of azahelicenes through Mallory reaction of imine precursors: corannulene substrates provide an exception to the rule in oxidative photocyclizations of diarylethenes

et al. 2021

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“…Previous synthesis of 2 mostly involves cyclization of N-benzylideneaniline (3a). [7][8][9][10] The oxidative photocyclization of N-benzylideneaniline (3a) was reported to proceed in the presence of strong acid [7][8][9] or Lewis acid. 10 However, all attempts resulted in low-yields.…”

Section: Introductionmentioning

confidence: 99%