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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
Author(s) -
Pérez Janaina Marinas,
Helten Holger,
Schnakenburg Gregor,
Streubel Rainer
Publication year - 2011
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201000861
Subject(s) - deconstruction (building) , ring (chemistry) , chemistry , stereochemistry , engineering , organic chemistry , waste management
Treatment of oxaphosphirane complex 1 , triflic acid (TfOH), and various aldehydes yielded 1,3,4‐dioxaphospholane complexes 5a , b – 7a , b after deprotonation with NEt 3 . In addition to NMR spectroscopy, IR spectroscopy, and MS data, the X‐ray structures of complexes 5a and 7a were determined. 31 P 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 observed 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.