Regioselectivity of Intramolecular Electrophilic Cyclization of 2-(Alkenylsulfanyl)thieno[2,3- d ]pyrimidin-4(3 H )-ones
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oselectivity of Intramolecular Electrophilic Cyclization of 2-(Alkenylsulfanyl)thieno[2,3-d]pyrimidin-4(3H)-ones with p-Methoxyphenyltellurium Trichloride M. M. Kuta,*, M. Yu. Onyskoa, S. Yu. Suikovb, and V. G. Lendela a b
Uzhhorod National University, Uzhhorod, 88000 Ukraine
Institute of Organic Chemistry, National Academy of Sciences of Ukraine, Kiev, 02660 Ukraine *e-mail: [email protected] Received March 27, 2020; revised April 4, 2020; accepted April 11, 2020
Abstract—3-Phenyl-2-(prop-2-en-1-ylsulfanyl)-5,6,7,8-tetrahydrobenzo[4,5]thieno[2,3-d]pyrimidin-4(3H)one reacted with 4-methoxyphenyltellurium trichloride in a regioselective manner to give angularly fused 1-{[dichloro(4-methoxyphenyl)-λ4-tellanyl]methyl}-4-oxo-5-phenyl-1,2,4,5,6,7,8,9-octahydrobenzo[4,5]thieno[3,2-e][1,3]thiazolo[3,2-a]pyrimidinium chloride. Electrophilic cyclization of 2-(prop-2-en-1-ylsulfanyl)and 2-(2-methylprop-2-en-1-ylsulfanyl)-5,6,7,8-tetrahydrobenzo[4,5]thieno[2,3-d]pyrimidin-4(3H)-ones with 4-methoxyphenyltellurium trichloride afforded linearly fused 3-{[dichloro(4-methoxyphenyl)-λ4-tellanyl]methyl}-2,3,6,7,8,9-hexahydro-5H-benzo[4,5]thieno[2,3-d][1,3]thiazolo[3,2-a]pyrimidin-5-one hydrochlorides. Regardless of the reactant ratio, the products were isolated as 1:1 complexes with 4-methoxyphenyltellurium trichloride. Keywords: electrophilic cyclization, p-methoxyphenyltellurium trichloride, regioselectivity, 2-(prop-2-en-1ylsulfanyl)-3-phenyl-5,6,7,8-tetrahydrobenzo[4,5]thieno[2,3-d]pyrimidin-4(3H)-one, 2-(alkenylsulfanyl)5,6,7,8-tetrahydrobenzo[4,5]thieno[2,3-d]pyrimidin-4(3H)-ones, 1-{[dichloro(4-methoxyphenyl)-λ4-tellanyl]methyl}-4-oxo-5-phenyl-1,2,4,5,6,7,8,9-octahydrobenzo[4,5]thieno[3,2-e][1,3]thiazolo[3,2-a]pyrimidinium chloride, 3-{[dichloro(4-methoxyphenyl)-λ4-tellanyl]methyl}-2,3,6,7,8,9-hexahydro-5H-benzo[4,5]thieno[2,3-d][1,3]thiazolo[3,2-a]pyrimidin-5-one hydrochloride
DOI: 10.1134/S1070428020100061 Annulation of an additional heterocycle on a fused pyrimidine ring via intramolecular electrophilic cyclization opens the possibility of obtaining new functionalized pyrimidine derivatives. In particular, convenient methods for fusion of thiazole and thiazine rings to quinazoline, thieno[2,3-d]pyrimidine, and pyrazolo[3,4-d]pyrimidine have been developed on the basis of intramolecular electrophilic cyclizations, and the reaction direction has been found to depend on both substrate structure and reaction conditions [1–17]. It is known that aryltellurium trichlorides are convenient cyclizing agents for the construction of heterocyclic systems with an exocyclic aryltellurium fragment [18–20]. As shown in [1–19], fusion of an additional ring to pyrimidine involves C=C double bond of the alkenyl fragment and nucleophilic sulfur atom and leads to the formation of linear polycyclic structures. In order to find out the possibility of fusion of an additional ring to pyrimidine with participation of nitrogen
atom as nucleophilic center, we selected 2-(alkenylsulfanyl)thieno[2,3-d]pyrimidin-4(3H)-ones 1, 3, and 4 as substra
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