Norbornadiene–Quadricyclane Valence Isomerism for a Tetraphosphorus Derivative The Netherlands Organization for Scientific Research (NOW/CW) is acknowledged for partial support (A.L.S., M.L., K.L.), as are the NSERC of Canada for a scholarship (S.B.C.), and EPSRC for funding phosphaorganometallic chemistry at Sussex University (J.F.N.). Dr. H. Zappey is thanked for the HR-MS spectra and J. C. Slootweg for his initiative.

Vlaar, Mark J. M.; Ehlers, Andreas W.; Schakel, Marius; Clendenning, Scott B.; Nixon, John F.; Lutz, Martin; Spek, Anthony L.; Lammertsma, Koop

doi:10.1002/1521-3773(20011203)40:23<4412::aid-anie4412>3.0.co;2-i

Cited by 21 publications

(1 citation statement)

References 17 publications

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“…No cage‐inversion reactions of optically active cage compounds have been reported in the literature, and P–C cage‐rearrangement reactions are rare. Most examples are based on photochemical activation of the cages,9,13,14 and sp 2 ‐hybridized cage phosphorus atoms have been identified by Binger et al as specifically reactive centers for rearrangement processes 15. The same seems to be true for the P 5 ‐deltacyclenes.…”

Section: Discussionmentioning

confidence: 97%

Optically Active P₅‐Deltacyclenes: A Unique Cage‐Inversion Reaction and Some Transition‐Metal Complexes of the Rearranged Cage

et al. 2015

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Cage-chiral P 5 -deltacyclene 1 is available as a pair of highly enriched P-C cage enantiomers 1′ and 1′′, which exist as pairs of epimers a and b. Deprotonation of cage atom P1 initiates a rearrangement reaction, in which P1 and the neighboring carbon atom C4, together with its substituent, change places to form optically active iso-P 5 -deltacyclene enantiomers 6′′ and 6′, again as pairs of epimers. The CD spectra of related pairs of optically active cages 1 and 6 consist of almost mirrorsymmetric curves, an indicator of mirror-symmetric cage structures. This surprising result was verified by an absolute structure determination of the W(CO) 5 complex 9a′′. With the exception of the two cage nuclei that had changed places in relation to starting material 1′, all other cage nuclei of rearrangement [a] 691 Scheme 2. Base-induced cage-rearrangement reactions of 1′ and 1′′ to form 6′′ and 6′, respectively. Expected and experimentally observed reaction pathways.

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Section: Discussionmentioning

confidence: 97%

Optically Active P₅‐Deltacyclenes: A Unique Cage‐Inversion Reaction and Some Transition‐Metal Complexes of the Rearranged Cage

et al. 2015

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1,4‐Addition von Grignard‐Reagentien an 2,4,6‐Tri‐tert‐butyl‐1,3,5‐triphosphabenzol

et al. 2003

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Grignard-Verbindungen (Organomagnesiumhalogenide) gehören zu den ältesten metallorganischen Reagentien, die breite Anwendung in der organischen Synthese gefunden haben.[2] Sie werden besonders für Additionen an polarisierte oder polarisierbare Kohlenstoff-Heteroatom-Mehrfachbindungen verwendet. Für die Addition an C-C-Mehrfachbindungen sind sie hingegen weniger geeignet. Triphosphabenzole wie das 2,4,6-Tri-tert-butyl-1,3,5-triphosphabenzol (1) [3] weisen zwar physikalisch-chemischen Messungen zufolge deutlich einen aromatischen Charakter auf, [4] sind aber trotzdem hochreaktive Verbindungen. So sind z. B. DielsAlder-Reaktionen [5] oder Lithiumalkoholat-Additionen unter Beteiligung aller drei P-C-Doppelbindungen [6] bei milden Bedingungen leicht durchführbar. Auch mit Silylenen, [7] Carbenen [8] oder Phosphinidenen [9] reagiert 1 bereitwillig, meist unter [2þ1]-Cycloaddition.Wir haben das Triphosphabenzol 1 mit den GrignardReagentien 2 a-d in THF umgesetzt und konnten nachweisen, dass 2 a-d schon bei À16 8C regio-und stereoselektiv mit 1 in einer formalen 1,4-Addition reagiert. Die Regioselektivität resultiert aus der Polarität der P-C-Doppelbindung, [10] wonach der organische Rest R der Grignard-Verbindung an ein Phosphoratom und das Metall an die C-4-Position addiert.Die cis-Stereoselektivität deutet darauf hin, dass es sich um eine synchrone oder polare Addition handelt. Es ist schon seit längerer Zeit bekannt, dass Monophosphabenzole mit lithium-wie auch magnesiumorganischen Verbindungen unter nucleophiler Addition reagieren. Nach Hydrolyse oder Reaktion mit Elektrophilen erhält man 1,2-Dihydrooder 1,4-Dihydrophosphinine. [11,12]

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Phosphacycles as Building Blocks for Main Group Cages

Townsend¹,

Shadbolt²,

Green³

et al. 2013

Angewandte Chemie

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As part of an ongoing interest in phosphorus/carbon compounds [1] we have focused on the reactivity and synthetic utility of possible sources of electrophilic PX 2 + and AsX 2 + fragments with a view to accessing novel main group architectures. It has been suggested [2] that there is an analogy between these reactive pnictenium species and carbenes. For example, Krossing and co-workers reported [3] that PX 3 (X = Br, I) reacts in CH 2 Cl 2 at À78 8C with Ag[Al(OR F ) 4 ] (R F = C(CF 3 ) 3 ) and P 4 to give the novel phosphorus rich molecules [P 5 X 2 ][Al(OR F ) 4 ] through a process thought to involve the insertion of the electrophilic carbenoid species [PX 2 ][Al-(OR F ) 4 ] into a PÀP bond of P 4 . Allied to this interesting observation is the report by Weigand and co-workers [4] that P 4 reacts, possibly by a similar reaction pathway, in a melt of Ph 2 PCl and GaCl 3 (1:1 at 60 8C) to form a structurally related molecule [P 5 Ph 2 ][GaCl 4 ]. Similarly, Burford and co-workers have used related methodology to prepare an extensive series of catena-phosphorus cations. [5]In our initial studies we focused on the reaction of 2,4,6tri-tert-butyl-1,3,5-triphosphabenzene (1) with latent sources of PX 2 + and AsX 2 + cations. It is interesting to note that 1 reacts with the Arduengo-type carbene 1,3,4,5-tetramethylimidazol-2-ylidene to give a ring-contracted 1,2,4-triphosphole, [6] whereas the silicon analogues, stable bis-(amine)silylenes, afford (4+1) cycloaddition products. [7] It has also been found experimentally that in the case of the reaction of 1 with sources of H + , CH 3 [9] h 1 -P-bonded cationic adducts are formed.As a first step we used density functional theory (see Supporting Information) to compare the relative thermodynamic stabilities of possible products which might result from the reaction of 1 with EX 3 (E = P, As ; X = Cl, Br) and the Lewis acid GaCl 3 . These calculations indicated that under thermodynamic control, a PX 2 + electrophile could react with 1 to give a h 1 -P-bonded adduct. For the phosphenium reagents, alternative products arising from electrophilic attack at carbon, ring contraction (analogous to the product from the reaction with an Arduengo carbene [6] ) or 1,2-addition are less favorable. In contrast, for the arsenium systems, although h 1 -As coordination is preferred, the energy difference between the alternative products is small. We can in fact envisage a possible reaction pathway to such a h 1 -P/Asbonded cation where the reaction of ECl 3 (E = P or As) with GaCl 3 leads to the direct formation of the ion-separated electrophilic species [ECl 2 ] + [GaCl 4 ] À , which can then be captured by 1 (Scheme 1 a). However, there is an alternative and perhaps more plausible pathway not involving a free ECl 2 + cation and that is through a synchronous S N 2 (P/As) push-pull (GaCl 3 ) process as illustrated in Scheme 1 b. [10] This alternative route can be related to the proposal by Wild, Radom, and co-workers that phosphenium cations can be readily transferred between unsaturate...

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Cited by 21 publications

References 17 publications

Optically Active P₅‐Deltacyclenes: A Unique Cage‐Inversion Reaction and Some Transition‐Metal Complexes of the Rearranged Cage

Optically Active P₅‐Deltacyclenes: A Unique Cage‐Inversion Reaction and Some Transition‐Metal Complexes of the Rearranged Cage

1,4‐Addition von Grignard‐Reagentien an 2,4,6‐Tri‐tert‐butyl‐1,3,5‐triphosphabenzol

Phosphacycles as Building Blocks for Main Group Cages

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Cited by 21 publications

References 17 publications

Optically Active P5‐Deltacyclenes: A Unique Cage‐Inversion Reaction and Some Transition‐Metal Complexes of the Rearranged Cage

Optically Active P5‐Deltacyclenes: A Unique Cage‐Inversion Reaction and Some Transition‐Metal Complexes of the Rearranged Cage

1,4‐Addition von Grignard‐Reagentien an 2,4,6‐Tri‐tert‐butyl‐1,3,5‐triphosphabenzol

Phosphacycles as Building Blocks for Main Group Cages

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Product

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Optically Active P₅‐Deltacyclenes: A Unique Cage‐Inversion Reaction and Some Transition‐Metal Complexes of the Rearranged Cage

Optically Active P₅‐Deltacyclenes: A Unique Cage‐Inversion Reaction and Some Transition‐Metal Complexes of the Rearranged Cage