1,2?5,5?5-azadiphospholium structures

Schmidpeter, Alfred; Polborn, Kurt

doi:10.1002/(sici)1098-1071(1997)8:4<347::aid-hc10>3.0.co;2-r

Cited by 13 publications

(7 citation statements)

References 5 publications

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“…1 Pyridinium allylides afforded indolizines via 1,5‐electrocyclization followed by 1,2‐elimination 2. In view of the reported close analogy between carbon and phosphorus compounds,3–5 we generated pyridinium‐2‐phosphaallylides ( 4 ) in situ , which underwent intramolecular 1,5‐electrocyclization followed by 1,2‐elimination to furnish 1,3‐bis(alkoxycarbonyl)‐2‐phosphaindolizines ( 6 ) (Scheme 2). 6, 7…”

Section: Introductionmentioning

confidence: 99%

1,5‐electrocyclization versus 1,5‐proton shift in imidazolium allylides and 2‐phospha‐allylides: a DFT investigation

Gupta

Bansal

Hopffgarten

et al. 2011

J of Physical Organic Chem

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The competitive 1,5‐electrocyclization versus intramolecular 1,5‐proton shift in imidazolium allylides and imidazolium 2‐phosphaallylides has been investigated theoretically at the DFT (B3LYP/6‐311 + +G**//B3LYP/6‐31G**) level. 1,5‐Electrocyclization follows pericyclic mechanism and its activation barrier is lower than that for the pseudopericyclic mechanism by ∼5–6 kcal mol−1. The activation barriers for 1,5‐electrocyclization of imidazolium 2‐phosphaallylides are found to be smaller than those for their nonphosphorus analogues by ∼3–5 kcal mol−1. There appears to be a good correlation between the activation barrier for intramolecular 1,5‐proton shift and the density of the negative charge at C8, except for the ylides having fluorine substituent at this position (7b and 8b). The presence of fluorine atom reduces the density of the negative charge at C8 (in 7b it becomes positively charged) and thus raises the activation barrier. The ylides 7f and 8f having CF3 group at C8, in preference to the 1,5‐proton shift, follow an alternative route leading to different carbenes which is accompanied by the loss of HF. The carbenes Pr7,8b–e resulting from intramolecular 1,5‐proton shift have a strong tendency to undergo intramolecular SN2 type reaction, the activation barrier being 7–28 kcal mol−1. Copyright © 2011 John Wiley & Sons, Ltd.

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Section: Introductionmentioning

confidence: 99%

1,5‐electrocyclization versus 1,5‐proton shift in imidazolium allylides and 2‐phospha‐allylides: a DFT investigation

Gupta

Bansal

Hopffgarten

et al. 2011

J of Physical Organic Chem

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“…Several simple cyclic salts, containing within a five-membered ring the moiety [ÀP(Ph 2 )P¼NÀP(Ph) 2 À] + , associated with a separate bromide anion, were reported. [14] The structure of 3 ( Figure 2) is a molecule with C 2v symmetry, both phosphorus atoms being in identical environments. In agreement with this observation, the two equal PÀN distances of 1.62 fell between the typical P¼N and PÀN values (1.59 and 1.68 , respectively), but closer to a P¼N double bond.…”

Section: Methodsmentioning

confidence: 99%

4,5‐Bis(diphenylphosphanyl)‐1,2,3‐triazole and Its Conversion to 1,1,3,3,‐Tetraphenyl‐1,3‐diphospha‐2,4,5,6‐tetraazapentalene

2003

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Towards a new family of ligands: The synthesis of the ligand HLT (depicted left) is described. Although HLT appears to be a simple chelating diphosphane, the tiazole proton can be removed with a base to produce an anionic diphosphane. Thus HLT can chelate in two modes: as a neutral rigid diphosphane, or as an anionic rigid diphosphane. Furthermore, HLT reacts in an unprecedented fashion with Me3SiN3 to give LT‐N (depicted right).

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“…[14] The structure of 3 ( Figure 2) is a molecule with C 2v symmetry, both phosphorus atoms being in identical environments. Several simple cyclic salts, containing within a five-membered ring the moiety [ÀP(Ph 2 )P¼NÀP(Ph) 2 À] + , associated with a separate bromide anion, were reported.…”

Section: Methodsmentioning

confidence: 99%

4,5‐Bis(diphenylphosphanyl)‐1,2,3‐triazole and Its Conversion to 1,1,3,3,‐Tetraphenyl‐1,3‐diphospha‐2,4,5,6‐tetraazapentalene

2003

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1,2?5,5?5-azadiphospholium structures

Cited by 13 publications

References 5 publications

1,5‐electrocyclization versus 1,5‐proton shift in imidazolium allylides and 2‐phospha‐allylides: a DFT investigation

1,5‐electrocyclization versus 1,5‐proton shift in imidazolium allylides and 2‐phospha‐allylides: a DFT investigation

4,5‐Bis(diphenylphosphanyl)‐1,2,3‐triazole and Its Conversion to 1,1,3,3,‐Tetraphenyl‐1,3‐diphospha‐2,4,5,6‐tetraazapentalene

4,5‐Bis(diphenylphosphanyl)‐1,2,3‐triazole and Its Conversion to 1,1,3,3,‐Tetraphenyl‐1,3‐diphospha‐2,4,5,6‐tetraazapentalene

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