Cyclooct-1-en-5-yne. Preparation, spectroscopic characteristics and chemical reactivity

✍ Scribed by Werner Leupin; Jakob Wirz

• Publisher: John Wiley and Sons
• Year: 1978
• Tongue: German
• Weight: 756 KB
• Volume: 61
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.19780610514

✦ Synopsis

Abstract

Cyclooct‐1‐en‐5‐yne (3) has been obtained as an isolable, but highly reactive hydrocarbon by oxidation of cyclooct‐5‐ene‐1, 2‐dihydrazone with lead tetraacetate (Scheme 2). Information regarding the structure and conformational mobility of 3 has been gained from the analysis of its ^1^H‐ and ^13^C‐NMR. spectra and was found to agree with the results of force field calculations. Photolysis (206 nm) of 3 in solution has induced cleavage to butatriene and butadiene. The first band in the photoelectron spectrum of 3 (I~v~ 9.10 eV) is attributed to ionization from a rather delocalized orbital with predominant weight of the double bond p‐AO's. Nevertheless, the high reactivity of 3 stems from the strained triple bond as evidenced by the reaction products obtained by pyrolysis, oxidation, Diels‐Alder addition, and 1, 3‐dipolar addition (Scheme 4).