An Approach to 1,3,4-Dioxaphospholane Complexes through an Acid-Induced Ring Expansion of an Oxaphosphirane Complex: The Problem of Construction and Deconstruction of O,P-Heterocycles

作者：Perez Janaina Marinas; Helten Holger; Schnakenburg Gregor; Streubel Rainer^*

来源：Chemistry-An Asian Journal, 2011, 6(6): 1539-1545.

DOI：10.1002/asia.201000861

• click chemistry
• DFT calculations
• epoxides
• heterocycles
• ring expansion

Treatment of oxaphosphirane complex 1, triflic acid (TfOH), and various aldehydes yielded 1,3,4-dioxaphospholane complexes 5a,b-7a,b after deprotonation with NEt3. In addition to NMR spectroscopy, IR spectroscopy, and MS data, the X-ray structures of complexes 5a and 7a were determined. P-31 NMR spectroscopic monitoring and DFT calculations provided insight into the reaction course and revealed the transient TfOH 1,3,4-dioxaphospholanium association complex TfOH-5a,b and/or TfOH-5a,b' as key reactive intermediates. Furthermore, it was ob-served that the five-membered ring system was cleaved upon warming and yielded side-on (E,Z)-methylenephosphonium complexes 8a,b if deprotonation did not occur at low temperature. Overall, a novel temperature-and acid-dependent construction and deconstruction process of the 1,3,4-dioxaphospholane ring system is described.

• 出版日期2011-6-6