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Electron‐Rich Aromatic 1,3‐Heterophospholes – Recent Syntheses and Impact of High Electron Density at σ 2 P on the Reactivity
Author(s) -
Heinicke Joachim W.
Publication year - 2016
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201500941
Subject(s) - chemistry , reactivity (psychology) , lone pair , electron counting , polar , alkylation , ring (chemistry) , crystallography , aromaticity , stereochemistry , catalysis , medicinal chemistry , electron , molecule , organic chemistry , medicine , physics , alternative medicine , pathology , quantum mechanics , astronomy
This account reviews recent syntheses, properties, and the reactivity of electron‐rich aromatic 1,3‐heterophospholes, with the focus on benzazaphospholes, but also with inclusion of 1,2,4‐diazaphospholes containing the N–C=P–C motif and related O‐ and S‐containing heterocycles. Effects of the high electron density at phosphorus, a consequence of the position of the lone‐pair donating nitrogen atom in conjugation with dicoordinated (σ 2 ) phosphorus and of the absence of P–N bonds, are illuminated by comparison of selected properties and reactions with those of less electron‐rich heterophospholes and phosphinines. Particular features of the electron‐rich heterocycles are CH‐lithiations of the P=CH fragment by t BuLi without addition at the P=C double bond in polar media, occurrence of inverse addition besides normal addition in less polar solutions, P ‐alkylation and catalytic P ‐arylation, and – last but not least – the avoidance of σ‐coordination of non‐zerovalent d 10 transition metals within the ring plane in favor of μ 2 ‐P and/or tilted η 1 ‐ P coordination.