Transannular Reactions of Two Parallel 1,3-Butadiynes: Syntheses, Structures, and Reactions of 1Azacyclotetradeca-3,5,10,12-tetrayne Derivatives

✍ Scribed by Erik M. Schmidt; Rolf Gleiter; Frank Rominger

• Publisher: John Wiley and Sons
• Year: 2003
• Tongue: English
• Weight: 200 KB
• Volume: 9
• Category: Article
• ISSN: 0947-6539
• DOI: 10.1002/chem.200390208

✦ Synopsis

Abstract

The synthesis of 1alkyl and 1aryl‐1‐azacyclotetradeca‐3,5,10,12‐tetraynes was achieved in a stepwise approach. The key intermediate was 1,13‐dibromotrideca‐2,4,9,11‐tetrayne (18). Reaction with methyl‐ (19 a), ethyl‐ (19 b), isopropyl‐ (19 c), n‐butyl‐ (19 d), and tert‐butylamine (19 e) as well as aniline (19 f) and p‐methoxyaniline (19 g) gave the corresponding 14‐membered tetraynes 20 a–20 g. The ring inversion process of 20 b was studied by variable temperature ^1^H NMR spectroscopy. From these measurements a value of 10.6 kcal mol^−1^ was calculated for Δ__G__^≠^. Xray investigations on single crystals of 20 b, 20 c, and 20 f revealed the axial position for the substituent at each nitrogen atom. For 20 b we encountered the chair conformation, for 20 c both chair and boat conformations, and for 20 f the boat conformation in the solid state. The reaction of 20 c with concentrated HCl in ethanol yielded 2,10‐dichloro‐6‐isopropyl‐6‐azatricyclo[9.3.0.0^4,8^]tetradeca‐1(11),2,4(8),9‐tetraene (25 c). Compound 25 c was oxidized by 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ) to 27 c. The structure of the latter was confirmed by Xray investigations. The reaction of 20 c in aqueous HCl lead to the formation of 10‐chloro‐2‐isopropyl‐1,3,4,6,7,8‐hexahydro‐2H‐benzo[g]isoquinolin‐9‐one (37 c). The structure of 37 c was verified by Xray studies on single crystals.