Synthesis and Chirality of Sixfold-Bridged Triple-Decker Phanes

✍ Scribed by Dipl.-Chem. Norbert Sendhoff; Dipl.-Chem. Karl-Heinz Weissbarth; Prof. Dr. Fritz Vögtle

• Publisher: John Wiley and Sons
• Year: 1987
• Tongue: English
• Weight: 323 KB
• Volume: 26
• Category: Article
• ISSN: 0044-8249
• DOI: 10.1002/anie.198707771

✦ Synopsis

tance ( 168.6 pm) is typical of phospha-alkenes.[" Within the three-membered ring, the smallest bond angle is at silicon, the largest at carbon. Together with the remarkably short C 1 -Si distance, the values found here establish the great similarity between the phosphasilirenes and the silirenes (silacyclopropenes), for which similar structural parameters have been

The formation and structure of 5 thus provide a further example of the analogy between the reaction behavior of phospha-alkynes and that of acetylenes."o' Experimental Procedures 5a: Irradiation of 4a (0.23 g, 2.3 mmol) and l a (OSOg, 1.17 mmol) in 80 mL of n-hexane with a high-pressure mercury lamp (Heraeus TQ 150) led, within 1.5 h, to quantitative conversion. After distillation of the n-hexane, 5a could be isolated as a bright yellow, unstable oil by HPLC (RP 18, acetonitrile as eluent).

5b: Analogously, irradiation of 4b (0.65 g, 3.65 mmol) and l a (0.75 g, 1.76 mmol) in 80 mL of n-hexane for 3 h gave a product mixture, from which 5b could be separated nearly quantitatively (based on 2a) by HPLC (Polygosil 60, n-hexane) or column chromatography (silica gel 60, petroleum ether, 40-60°C).

6 : W(CO), (2.4 g, 6.9 mmol) in 80 mL of T H F was irradiated until approximately 80% of the amount of C O necessary to form [W(CO),(thf)l had evolved and was removed. Compound. 5b, prepared from 4b (0.97 g, 5.4 mmol) and l a (I. 10 g, 2.6 mmol) in 80 mL of n-hexane, was then added to this solution and the resulting mixture was stirred for 30 min at room temperature. The solvent was removed under vacuum, petroleum ether 40-60°C was added, and W(CO), was filtered off. Yellow crystals of 6 formed from the reddish brown solution at -18°C. These were recrystallized twice from pentane. Yield: 0.91 g (55% based on Za), dec. > 140°C.