Frustrated Lewis Pairs and Ring-Opening of THF, Dioxane, and Thioxane

Birkmann, B.; Voss, Tanja; Geier, Stephen J.; Ullrich, Matthias S.; Kehr, Gerald; Erker, Gerhard; Stephan, Douglas W.

doi:10.1021/om1003896

Cited by 94 publications

(70 citation statements)

References 42 publications

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“…[15] Such reactions have been extended to a variety of FLPs and other heterocyclic substrates. [175] For example, reaction of 2,6-lutidine with a THF solution of B(C 6 F 5 ) 3 led to 2,6-Me 2 C 5 H 3 N(CH 2 ) 4 OB(C 6 F 5 ) 3 (416; Scheme 119), while similar reactions with C 6 H 5 CH 2 NMe 2 and t Bu 2 PH gave the analogues 417 and 418. 1,4-dioxane and thioxane could also be ring opened to give 419-425 (Scheme 120).…”

Section: Flp Ring-opening Reactions With Heterocyclesmentioning

confidence: 99%

Frustrated Lewis Pair Chemistry: Development and Perspectives

2015

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Frustrated Lewis pairs (FLPs) are combinations of Lewis acids and Lewis bases in solution that are deterred from strong adduct formation by steric and/or electronic factors. This opens pathways to novel cooperative reactions with added substrates. Small-molecule binding and activation by FLPs has led to the discovery of a variety of new reactions through unprecedented pathways. Hydrogen activation and subsequent manipulation in metal-free catalytic hydrogenations is a frequently observed feature of many FLPs. The current state of this young but rapidly expanding field is outlined in this Review and the future directions for its broadening sphere of impact are considered.

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Section: Flp Ring-opening Reactions With Heterocyclesmentioning

confidence: 99%

Frustrated Lewis Pair Chemistry: Development and Perspectives

2015

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“…These compounds (13)(14)(15)r earrange slowly in solution at room temperature to afford the enone derivatives 16 and 17 (Scheme4). The formation of 16 from the sterically better shielded 13 requires1 3days, whereas with neopentyl groups attached to aluminum (15)t he new product (17)i sq uantitatively formed after ar elatively short time of two days.…”

Section: Reactionswith Cyclopropenone and Related Compoundsmentioning

confidence: 99%

Al/P‐ and Ga/P‐Based Frustrated Lewis Pairs and Electronically Unsaturated Substrates: Ring Cleavage and Ring Closure, C−C and C−N Bond Formation

Pleschka

Uebing

Lange

et al. 2019

Chemistry A European J

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Al/P‐ and Ga/P‐based frustrated Lewis pairs (FLPs) reacted with an azirine under mild conditions under cleavage of the heterocycle on two different positions. Opening of the C−C bond yielded an unusual nitrile–ylide adduct in which a C−N moiety coordinated to the FLP backbone. Cleavage of a C−N bond afforded the thermodynamically favored enamine adduct with the N atom bound to P and Al or Ga atoms. Ring closure was observed upon treatment of an Al/P FLP with electronically unsaturated substrates (4‐(1‐cyclohexenyl)‐1‐aza‐but‐1‐en‐3‐ynes) and yielded by C−N bond formation hexahydroquinoline derivatives, which coordinated to the FLP through P−C and Al−C bonds. Diphenylcyclopropenone showed a diverse reactivity, which depending on steric shielding and the polarizing effect of Al or Ga atoms afforded different products. An AltBu2/P FLP yielded an adduct with the C=O group coordinated to P and Al. The dineopentyl derivative gave an equilibrium mixture consisting of a similar product and a simple adduct with O bound to Al and a three‐coordinate P atom. Both compounds co‐crystallize. The Ga/P FLP only formed the simple adduct with the same substrate. Rearrangement resulted in all cases in C3‐ring cleavage and migration of a mesityl group from P to a former ring C atom by C−C bond formation. Diphenylthiocyclopropenone (evidence for the presence of P=C bonds) and an imine derivative afforded similar products.

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“…[33] Herein, we exploit this reactivity to prepare a dissymmetric macrocyclic species through reaction of 13 with THF. This reaction affords the new macrocycle [tBu 2 …”

Section: And Mes 2 P(h)c 6 F 4 B(h)-mentioning

confidence: 99%

Synthesis and Reactivity of Alkynyl‐Linked Phosphonium Borates

Zhao

Lough

Stephan

2011

Chemistry A European J

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The phosphine tBu(2 PC[triple bond]CH (1) was reacted with B(C(6)F(5)) to give the zwitterionic species tBu(2)P(H)C[triple bond]CB(C(6)F(5))(3) (2). The analogous species tBu(2)P(Me)C[triple bond]CB(C(6)F(5))(3) (3), tBu(2)P(H)C[triple bond]CB(Cl)(C(6)F(5))(2) (4), tBu(2)P(H)C[triple bond]CB(H)(C(6)F(5))(2) (5), and tBu(2)P(Me)C[triple bond]CB(H)(C(6)F(5))(2) (6) were also prepared. The salt [tBu(2)P(H)C[triple bond]CB(C(6)F(5))(2)(THF)][B(C(6)F(5))(4)] (7) was prepared through abstraction of hydride by [Ph(3)C][B(C(6)F(5))(4)]. Species 5 reacted with the imine tBuN=CHPh to give the borane-amine adduct tBu(2)PC[triple bond]CB[tBuN(H)CH(2)Ph](C(6)F(5))(2) (8). The related phosphine Mes(2)PC[triple bond]CH (9; Mes=C(6)H(2)Me(3)) was used to prepare [tBu(3)PH][Mes(2)PC[triple bond]CB(C(6)F(5))(3)] (10) and generate Mes(2)PC[triple bond]CB(C(6)F(5))(2). The adduct Mes(2)PC[triple bond]CB(NCMe)(C(6)F(5))(2) (11) was isolated. Reaction of Mes(2)PC[triple bond]CB(C(6)F(5))(2) with H(2) gave the zwitterionic product (C(6)F(5))(2)(H)BC(H)=C[P(H)Mes(2)][(C(6)F(5))(2)BC[triple bond]CP(H)Mes(2)] (12). Reaction of tBu(2)PC[triple bond]CB(C(6)F(5))(2), a phosphine-borane generated in situ from 5, with 1-hexene gave the species [tBu(2)PC[triple bond]CB(C(6)F(5))(2)](CH(2)CHnBu)[tBu(2)PC[triple bond]CB(C(6)F(5))(2)] (13) and subsequent reaction with methanol or hexene resulted in the formation of [tBu(2)P(H)C[triple bond]CB(C(6)F(5))(2)](CH(2)CHnBu)[tBu(2)PC[triple bond]CB(C(6)F(5))(2)](OMe) (14) or the macrocycle {[tBu(2)PC[triple bond]CB(C(6)F(5))(2)](CH(2)CH(2)nBu)}(2) (15), respectively. In a related fashion, the reaction of 13 with THF afforded the macrocycle [tBu(2)PC[triple bond]CB(C(6)F(5))(2)](CH(2)CHnBu)[tBu(2)PC[triple bond]CB(C(6)F(5))(2)][O(CH(2))(4)] (16), although treatment of tBu(2)PC[triple bond]CB(C(6)F(5))(2) with THF lead to the formation of {[tBu(2)[triple bond]CB(C(6)F(5))(2)][O(CH(2))(4)]}(2) (17). In a related example, the reaction of Mes(2)PC[triple bond]CB(C(6)F(5))(2) with PhC[triple bond]CH gave {[Mes(2)PC[triple bond]CB(C(6)F(5))(2)](CH[triple bond]CPh)}(2) (18). Compound 5 reacted with AlX(3) (X=Cl, Br) to give addition to the alkynyl unit, affording (C(6)F(5))(2)BC(H)=C[P(H)tBu(2)](AlX(3)) (X=Cl 19, Br 20). In a similar fashion, 5 reacted with [Zn(C(6)F(5))(2)]⋅C(7)H(8), [Al(C(6)F(5))(3)]⋅C(7)H(8), or HB(C(6)F(5))(2) to give (C(6)F(5))(3)BC(H)=C[P(H)tBu(2)][Zn(C(6)F(5))] (21), (C(6)F(5))(3)BC(H)=C[P(H)tBu(2)][Al(C(6)F(5))(2)] (22), or [(C(6)F(5))(2)B](2)HC=CH[P(H)tBu(2)] (23), respectively. The implications of this reactivity are discussed.

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Frustrated Lewis Pairs and Ring-Opening of THF, Dioxane, and Thioxane

Cited by 94 publications

References 42 publications

Frustrated Lewis Pair Chemistry: Development and Perspectives

Frustrated Lewis Pair Chemistry: Development and Perspectives

Al/P‐ and Ga/P‐Based Frustrated Lewis Pairs and Electronically Unsaturated Substrates: Ring Cleavage and Ring Closure, C−C and C−N Bond Formation

Synthesis and Reactivity of Alkynyl‐Linked Phosphonium Borates

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