Preparation and Structures of Cyclotetradeca-4,11-diynone, Cyclotetradeca-4,11-diyne-1,8-dione, Their Exomethylene Derivatives, and 1,8-Dioxacyclotetradeca-4,11-diyne

✍ Scribed by Gleiter, Rolf ;Ramming, Matthias ;Weigl, Hagen ;Wolfart, Volker ;Irngartinger, Hermann ;Oeser, Thomas

• Book ID: 102902549
• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 564 KB
• Volume: 1997
• Category: Article
• ISSN: 0947-3440
• DOI: 10.1002/jlac.199719970734

✦ Synopsis

Abstract

The following 14‐membered ring diynes have been synthesized: cyclotetradeca‐4,11‐diynone (4), cyclotetradeca‐4,11‐diyne‐1,8‐dione (6), the corresponding exomethylene derivatives 5 and 7, as well as 1,8‐dioxacyclotetradeca‐4,11‐diyne (8). The synthesis of the diketal of 4 was achieved by the reaction of the ethylene ketal of 1,5‐dibromopentan‐3‐one (9) with the dilithium salt of 1,8‐nonadiyne. Similarly, the diketal of 6 was prepared from the dilithium salt of the ethylene ketal of 1,8‐nonadiyn‐5‐one 11 with 9. The unprotected ketones 4 and 6 were obtained by treating the ketals 10 and 14, respectively, with HCl. The ketones 4 and 6 were transformed to the exomethylene derivatives by a Wittig reaction. The reaction of the dilithium salt of 5‐oxanona‐1,8‐diyne (16a) with 1,5‐dibromo‐3‐oxapentane (15) yielded 8. X‐ray investigations of single crystals of 6 and 8 revealed chair conformations with a zig–zag arrangement, employing two anti orientations of the two chains between the triple bonds. A zig–zag arrangement of the chain containing the carbonyl group was also found in 4. In 3b and 7 C~i~ symmetry was found, with only one anti conformation in each chain. Molecule 6 crystallizes with C~2__h__~ symmetry and 8 with a center of symmetry.