[3 + 2] Cycloaddition of Diazomethane Derivatives to Perfluoro-2-phosphapropene

✍ Scribed by J. Grobe; A. Armbrecht; D. Le Van; B. Krebs; J. Kuchinke; M. Läge; E.-U. Würthwein

• Publisher: John Wiley and Sons
• Year: 2001
• Tongue: German
• Weight: 195 KB
• Volume: 627
• Category: Article
• ISSN: 0372-7874
• DOI: 10.1002/1521-3749(200106)627:6<1241::aid-zaac1241>3.0.co;2-4

✦ Synopsis

Perfluoro-2-phosphapropene (1) reacts with diazo compounds R(H)C=N 2 (R = H (2 a), Ph (2 b), CO 2 Et (2 c), Me 3 Si (2 d)) at low temperatures regioselectively yielding via 1,3-H shift the novel 1,2,3-diazaphospholes 4 a±d. The mesomerically stabilized compounds 4 b and 4 c were characterized by NMR spectroscopy and single crystal X-ray diffraction studies. Using diphenyldiazomethane 5 as partner for 1, the cycloaddition is spontaneously followed by N 2 elimination to give the crystalline phosphirane derivative 7. The analogous reaction of 1 with 9-diazofluorene 9 unex-pectedly leads to the so-far unknown 1,2-diphosphinane compound 11. Quantum chemical calculations for the gas phase on DFT and RHF level prove that for both the perhydro-and the perfluoro-2-phosphapropene the [3 + 2]-cycloaddition is kinetically determined and that, due to high stability of the products, the thermodynamic equilibrium with the slightly more stable isomers is not accessible.