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<p>A new route was developed to prepare <i>cis,trans,cis</i>-ethyl 9-difluoromethyl-9-hydroxyhexahydropyrido[2,1-<i>b</i>]quinazoline-8-carboxylates or a mixture of <i>trans</i>- and <i>cis</i>-ethyl 7-R-9-methylhexahydropyrido[2,1-<i>b</i>]quinazoline-8-carboxylates (R = Me, Ph) by the three-component cyclization of α,β-enals and 2-(aminomethyl)aniline using ethyl 4,4-difluoroacetoacetate and ethyl acetoacetate, respectively, as a 3-oxo ester component under mild conditions. On heating, an alternative route to <i>trans</i>- and <i>cis</i>-(2,2-difluoro-1-hydroxyethyl)tetrahydropyrido[2,1-<i>b</i>]quinazolin-9-ones is the major one for ethyl 4,4-difluoroacetoacetate. The diastereomeric structures of the heterocycles were established by <sup>1</sup>H, <sup>19</sup>F, and <sup>13</sup>C NMR spectroscopy, including 2D <sup>1</sup>H—<sup>13</sup>C HSQC/HMBC and <sup>1</sup>H—<sup>1</sup>H NOESY experiments, and X-ray diffraction.</p>

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Alternative pathways of cyclization of methyl- and difluoromethyl-3-oxo esters with α,β-enals and 2-aminomethylaniline into pyrido[2,1-b]quinazolines

  • 期刊论文

  • 发表日期：

    2025年11月1日

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  • M. V. Goryaeva,
  • S. O. Kushch,
  • Ya. V. Burgart,
  • M. A. Ezhikova,
  • M. I. Kodess,
  • P. A. Slepukhin,
  • V. I. Saloutin

摘要

A new route was developed to prepare cis,trans,cis-ethyl 9-difluoromethyl-9-hydroxyhexahydropyrido[2,1-b]quinazoline-8-carboxylates or a mixture of trans- and cis-ethyl 7-R-9-methylhexahydropyrido[2,1-b]quinazoline-8-carboxylates (R = Me, Ph) by the three-component cyclization of α,β-enals and 2-(aminomethyl)aniline using ethyl 4,4-difluoroacetoacetate and ethyl acetoacetate, respectively, as a 3-oxo ester component under mild conditions. On heating, an alternative route to trans- and cis-(2,2-difluoro-1-hydroxyethyl)tetrahydropyrido[2,1-b]quinazolin-9-ones is the major one for ethyl 4,4-difluoroacetoacetate. The diastereomeric structures of the heterocycles were established by 1H, 19F, and 13C NMR spectroscopy, including 2D 1H—13C HSQC/HMBC and 1H—1H NOESY experiments, and X-ray diffraction.