TY - JOUR

T1 - Expedient synthesis of 1,2,4-triazinyl substituted benzo[c]coumarins via double oxidation strategy

AU - Fatykhov, Ramil f.

AU - Khalymbadzha, Igor a.

AU - Sharapov, Ainur d.

AU - Potapova, Anastasia p.

AU - Starnovskaya, Ekaterina s.

AU - Kopchuk, Dmitry s.

AU - Chupakhin, Oleg n.

N1 - This work was supported by the Russian Science Foundation (grant no. 21-73-00214).

PY - 2023

Y1 - 2023

N2 - Herein, we report a convenient one-pot synthesis of 1,2,4-triazinyl derivatives of benzocoumarins. The proposed approach consists of the nucleophilic addition of tetrahydrobenzo annulated dimethoxycoumarin to 1,2,4- triazines followed by double oxidation of both dihydrotriazine and tetrahydrobenzo groups with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). The nucleophilic addition of the dimethoxycoumarin to 1,2,4-triazines was carried out in the presence of three-fold excess of methanesulfonic acid in DCM at room temperature. It takes place between positions 8 and 5 of coumarin and 1,2,4-triazine, respectively. The double oxidation step was carried out with 3.6 equivalent of DDQ. Selective oxidation of dihydrotriazine moiety, without affecting the tetrahydrobenzo fragment, was achieved using 1.2 equivalent of tetrachlorobenzoquinone (TCQ). The differences in the oxidation with TCQ and DDQ appear to be related to the higher oxidative potential of DDQ in contrast to TCQ. The advantages of the method are the elimination of the use of transition metals, the availability of starting materials, and the simplicity of the procedure. The proposed approach provides a two-step one-pot protocol for the synthesis of triazinyl benzocoumarins, precursors for the preparation of push-pull pyridinyl chromophore.

AB - Herein, we report a convenient one-pot synthesis of 1,2,4-triazinyl derivatives of benzocoumarins. The proposed approach consists of the nucleophilic addition of tetrahydrobenzo annulated dimethoxycoumarin to 1,2,4- triazines followed by double oxidation of both dihydrotriazine and tetrahydrobenzo groups with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). The nucleophilic addition of the dimethoxycoumarin to 1,2,4-triazines was carried out in the presence of three-fold excess of methanesulfonic acid in DCM at room temperature. It takes place between positions 8 and 5 of coumarin and 1,2,4-triazine, respectively. The double oxidation step was carried out with 3.6 equivalent of DDQ. Selective oxidation of dihydrotriazine moiety, without affecting the tetrahydrobenzo fragment, was achieved using 1.2 equivalent of tetrachlorobenzoquinone (TCQ). The differences in the oxidation with TCQ and DDQ appear to be related to the higher oxidative potential of DDQ in contrast to TCQ. The advantages of the method are the elimination of the use of transition metals, the availability of starting materials, and the simplicity of the procedure. The proposed approach provides a two-step one-pot protocol for the synthesis of triazinyl benzocoumarins, precursors for the preparation of push-pull pyridinyl chromophore.

UR - http://www.scopus.com/inward/record.url?partnerID=8YFLogxK&scp=85162154775

UR - https://elibrary.ru/item.asp?id=54268147

U2 - 10.15826/chimtech.2023.10.2.05

DO - 10.15826/chimtech.2023.10.2.05

M3 - Article

VL - 10

JO - Chimica Techno Acta

JF - Chimica Techno Acta

SN - 2409-5613

IS - 2

M1 - 202310205

ER -