Transformation of a 1-Zirconacyclopent-3-yne, a Five-Membered Cycloalkyne, into a 1-Zirconacyclopent-3-ene and Formal “1-Zirconacyclopenta-2,3-dienes”

✍ Scribed by Noriyuki Suzuki; Daisuke Hashizume; Hiroyuki Koshino; Teiji Chihara

• Publisher: John Wiley and Sons
• Year: 2008
• Tongue: English
• Weight: 345 KB
• Volume: 47
• Category: Article
• ISSN: 0044-8249
• DOI: 10.1002/anie.200800739

✦ Synopsis

Preparation of 8 a: Complex 3 (75.3 mg, 0.105 mmol) and KC 8 (46 mg; K atoms: 0.25 mmol) were suspended in THF (1.5 mL) at room temperature, and the resulting mixture was stirred for 1 h. The deep blue mixture was then cooled to À78 8C, and iodomethane (68 mg, 0.48 mmol) was added dropwise. The mixture immediately turned brown. It was warmed to room temperature and stirred for 1 h. 1 H NMR spectroscopy showed clean formation of 8 a (83 %). Volatiles were removed in vacuo, and the residue was dissolved in hexane. The solution was filtered, and the filtrate was concentrated and cooled at À30 8C to give 8 a as red crystals (53.2 mg, 68 %). 1 H NMR (600 MHz, C 6 D 6 , Me 4 Si): d = 1.08 (t, J = 7.6 Hz, 3 H), 1.12 (t, J = 7.6 Hz, 3 H), 1.16 (t, J = 7.6 Hz, 3 H), 1.18 (t, J = 7.6 Hz, 3 H), 1.62 (s, 3 H), 2.19 (s, 3 H), 2.45 (q, J = 7.6 Hz, 2 H), 2.51 (q, J = 7.6 Hz, 2 H), 2.54 (q, J = 7.6 Hz, 2 H), 2.58 (q, J = 7.6 Hz, 2 H), 5.01 (s, 5 H), 5.45 (s, 5 H), 7.09 (d, J = 8.5 Hz, 2 H), 7.11 (d, J = 8.1 Hz, 2 H), 7.16 (d, J = 7.5 Hz, 2 H), 7.16 (d, J = 7.6 Hz, 2 H), 7.53 (d, J = 8.1 Hz, 2 H), 7.62 (d, J = 8.5 Hz, 2 H), 7.70 (d, J = 7.6 Hz, 2 H), 7.73 ppm (d, J = 7.5 Hz, 2 H).

Compound 8 b was prepared similarly by using trimethyltin chloride. (Caution! Trimethyltin chloride is highly toxic and must be handled in a fume hood.)

Crystallographic data of 8 a: C 50 H 52 Zr, FW = 744.18, monoclinic, space group P2 1 /c (no. 14), a = 19.486(4), b = 8.6745( 14), c = 23.967(4) , b = 105.982(12)8, V = 3897.6(12) 3 , Z = 4, 1 calc = 1.269 g cm À3 , m = 3.159 cm À1 , l = 0.71073 , T = 90 K, 8946 unique (R int = 0.071) and 669 refined parameters, R = 0.0457, wR 2 = 0.1107. [9] .