A Convenient Synthesis of 2, 3‐Dihydro‐4H‐thiopyrano[2, 3‐b]‐, ‐[2, 3‐c]‐, or ‐[3, 2‐c]pyridin‐4‐ones by the Reaction of the Corresponding 1‐(Chloropyridinyl)alk‐2‐en‐1‐ones with NaSH. Issue 4 (10th April 2013)

• Record Type: Journal Article
• Authors: Kobayashi, Kazuhiro; Imaoka, Ayumi
• Is Part Of: Helvetica chimica acta. Volume 96:Issue 4(2013:Apr.)
• Page Start: 624
• Page End: 632
• Publication Date: 2013-04-10
• Subjects: Chemistry -- Periodicals; Chemistry, Analytical -- periodicals; Chimie -- Périodiques; 540
• DOI: 10.1002/hlca.201200543
• Languages: English
• ISSNs: 0018-019X

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>2, 3‐Dihydro‐4<italic>H</italic>‐thiopyrano[2, 3‐<italic>b</italic>]pyridin‐4‐ones <bold>4</bold> were prepared by a three‐step sequence from commercially available 2‐chloropyridine (<bold>1</bold>). Thus, successive treatment of <bold>1</bold> with ⁱPr₂NLi (LDA) and <italic>α</italic>, <italic>β</italic>‐unsaturated aldehydes gave 1‐(2‐chloropyridin‐3‐yl)alk‐2‐en‐1‐ols <bold>2</bold>, which were oxidized with MnO₂ to 1‐(2‐chloropyridin‐3‐yl)alk‐2‐en‐1‐ones <bold>3</bold>. The reactions of <bold>3</bold> with NaSH⋅<italic>n</italic> H₂O proceeded smoothly at 0° in DMF to provide the desired thiopyranopyridinones. Similarly, 2, 3‐dihydro‐4<italic>H</italic>‐thiopyrano[2, 3‐<italic>c</italic>]pyridin‐4‐ones <bold>8</bold> and 2, 3‐dihydro‐4<italic>H</italic>‐thiopyrano[3, 2‐<italic>c</italic>]pyridin‐4‐ones <bold>12</bold> were obtained starting from 3‐chloropyridine (<bold>5</bold>) and 4‐chloropyridine (<bold>9</bold>), respectively.</p> </abstract>