A FACILE METHOD FOR SYNTHESIS OF HETEROCYCLES CONTAINING TETRAHYDROBENZO[4,5]THIENO[2,3-d]PYRIMIDINE AND COUMARIN MOIETIES

Abstract

2-(2-Oxo-2H-1-benzopyran-3-yl)-5,6,7,a-tetrahydro-3H-benzo [4,5]thieno[2,3-d]pyrimidin-4-ones (4a.bi have been synthesized via a rearrangement of 2-(A/-3-carbamoyl-4,5,6,7-tetrahydrobenzo[b]thiophen-2-yl)imino-2H-1benzopyran-3-carboxamides (3a.b). The tetrahydrobenzo[ö]thiophenes 3 have been conveniently prepared by the reaction of 2-imino-2H-1-benzopyran-3-carboxamides (la£) with 2-amino-4,5,6,7-tetrahydrobenzo[ö]thiophene-3carboxamide (2) in glacial acetic acid.

Convenient synthesis of substituted 2‐(2‐iminocoumarin‐3‐yl)thieno[2,3‐d]pyrimidin‐4‐ones

“…Thus with the aim to prove the presence of imino‐group in the molecule of these derivatives we performed their acidic hydrolysis (HCl) in 2‐propanol‐water mixture. The obtained products appeared to be the same as previously reported 3‐(4‐oxo‐3,4‐dihydrothieno[2,3‐ d ]pyrimidin‐2‐yl)coumarins 7a , 7b , 7c [34–36] (Table 1).…”

“…It is known that the interaction of 2‐iminocoumarin‐3‐carboxamides with arylamines in the glacial acetic acid leads to formation of 2‐ N ‐aryliminocoumarin‐3‐carboxamides [34–38]. We applied a similar reaction to obtain the key‐intermediates, which apparently were 2‐(3‐carbamoyl‐2‐thienylimino)coumarin‐3‐carbonitriles 3 by interaction between 2‐iminocoumarin‐3‐carbonitriles 1 and 2‐aminothiophen‐3‐carboxamides 2.…”

“…Recently it was shown that “recyclization” of 2‐iminocoumarin‐3‐carboxamides under the action of binucleophlic reagents results in various 3‐heterylcoumarins [25, 26, 32–37]. According to the proposed mechanism of these reactions the carboxamide group of 2‐iminocoumarin‐3‐carboxamide serves as precursor of lactone CO group of the resulting 3‐heterylcoumarin.…”

Recyclization of 2-Imino-2H-1-benzopyrans with Nucleophilic Reagents - Reaction of 2-Iminocoumarin-3-carboxamides with 2-Aminothiophene-3-carboxamides

“…20 However, this method is difficult to apply to the synthesis of 2-(coumarin-3-yl)thieno[2,3-d]pyrimidin-4-ones, because the starting thieno [2,3-d]pyrimidin-4-one-2-acetic acid derivatives require complex synthetic procedures. 21 In previous papers 22, 23 we described a simpler method for the synthesis of substituted 2-(coumarin-3-yl)-3,4,5,6,7,8hexahydrobenzothieno[2,3-d]pyrimidin-4-ones by rearrangement of 2-substituted coumarin-3-carboxamides, which can also be applied to the synthesis of other 3hetarylcoumarins. 24 As an extension of our work related to the recyclization of 2-imino-2H-1-benzopyrans by nucleophilic reagents we investigated the scope of this approach for the synthesis of a range of 2-(coumarin-3-yl)thieno [2,3-…”

Synthesis of 5‐methyl‐4‐oxo‐2‐(coumarin‐3‐yl)‐N‐aryl‐3,4‐dihydrothieno[2,3‐d]‐pyrimidine‐6‐carboxamides

“…Earlier, we reported the interaction of 2-iminocoumarin-3-carboxamides with 2-aminothiophene-3-carboxamides, which leads to the formation of 2-(coumarin-3-yl)thieno [2,3-d]pyrimidin-4-ones, and developed a method for the synthesis of this class of compounds via cyclization of 2-(3-carbamoyl-2-thienylimino)coumarine-3-carboxamides in DMF [5][6][7]. To scrutinize the scope and limitations of this method, we studied its capability with respect to the synthesis of 5-methyl-4-oxo-2-(coumarin-3-yl)-N-aryl-3,4-dihydrothieno [2,3-d]pyrimidine-6carboxamides 4.…”