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Diphosphonio Dihydrophosphetide and 1,2‐Diphospholide Cations
Author(s) -
Jochem Georg,
Schmidpeter Alfred,
Nöth Heinrich
Publication year - 1996
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.19960020215
Subject(s) - chemistry , ring (chemistry) , triethylamine , allylic rearrangement , halogen , adduct , medicinal chemistry , condensation , stereochemistry , catalysis , organic chemistry , alkyl , physics , thermodynamics
Condensation of a 1,3‐diphosphoniopropenide cation at its reactive 1,3‐positions with a dichlorophosphine in the presence of triethylamine provides a route to 2,4‐diphosphoniodihydrophosphetide cations. An excess of dichlorophosphine in the presence of an additional reducing agent results in a ring expansion and yields 3,5‐diphosphoniodihydro‐1,2‐diphospholide cations. The chlorosubstituted cation derived from PCl 3 can be further reduced to the hydrolytically stable 3,5‐diphosphonio‐1,2‐diphospholide cation. It adds halogen to the PP bond and can easily be regained from the halogen adduct. Structural comparison of the 1,2‐diphenyl‐ and 1,2‐dichlorodihydro‐1,2‐diphospholide cation with the 1,2‐diphospholide cation shows three stages of interaction of the C 3 and the P 2 entities of the ring: no conjugation in the first case, hyperconjugative extension of the allylic system to include the phosphorus atoms in the second case and cyclic π conjugation in the third.