A P–H functionalized Al/P-based frustrated Lewis pair – hydrophosphination of nitriles, ring opening with cyclopropenones and evidence of PC double bond formation

Keweloh, Lukas; Aders, Niklas; Hepp, Alexander; Pleschka, Damian; Würthwein, Ernst‐Ulrich; Uhl, Werner

doi:10.1039/c8dt01836g

Cited by 24 publications

(30 citation statements)

References 96 publications

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“…The new P1−C40 bond is with 175.1(2) pm relatively short compared with the P−C bond lengths observed in the O compounds. In addition, an unusual lowfield shift was observed for the 31 P NMR resonance of 21 ( δ =107.1 ppm) which approaches values observed for alkenylphosphonium cations with P=C double bonds . The Ga/P FLP 4 afforded directly the ring cleavage product 23 after a short reaction time of 30 minutes at room temperature.…”

Section: Resultsmentioning

confidence: 62%

“…Only recently we reported on the reaction of the P−H functionalized FLP 3 with diphenylcyclopropenone, which resulted in ring opening by shift of the P bound H atom to a C atom of the cyclopropene ring below room temperature . We assumed that FLPs 1 and 2 , which have two mesityl groups attached to P, are not able to show similar reactions, because in that case the migration of a bulky mesityl group by cleavage of a P−C bond is required.…”

Section: Resultsmentioning

confidence: 99%

“…The chemical shift of the P atom is with δ =101.6 ppm comparable to that of the Al compound. Recently, we isolated similar products from the reaction of the P−H functionalized FLP 3 with diphenyl thiocyclopropenone . The approach to an intramolecular stabilized alkenylphosphonium salt was more pronounced in that case with δ ( 31 P)=133 ppm and a P−C distance of 168.9(1) pm.…”

Section: Resultsmentioning

confidence: 99%

“…The facile synthetic procedure allowed the generation of functionalized compounds that had, beside a protecting mesityl substituent, an alkynyl group or a H atom ( 3 ) attached to phosphorus. The latter showed a fascinating reactivity with the transfer of the phosphorus‐bound H atom to substrates which were activated by coordination to the FLP backbone through its typical donor–acceptor functionality . Ga atoms are softer Lewis acids compared with Al atoms and should allow a modulation of the FLP properties.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Resultsmentioning

confidence: 62%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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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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“…[61,62] Throughout the Fischer-Tropsch reaction chemistry literature,w e cannot find any report in which ap roton is transferred directly to the carbon of CO without an external agent (Lewis acid or proton source) or beginning from ah ydride source. [71] Other examples involving Frustrated Lewis Pairs (FLPs) have been noted, [72][73][74] but we can find no prior reports of unassisted functionalization of CO (other than when hydride is part of the starting material). [71] Other examples involving Frustrated Lewis Pairs (FLPs) have been noted, [72][73][74] but we can find no prior reports of unassisted functionalization of CO (other than when hydride is part of the starting material).…”

Section: Angewandte Chemiementioning

confidence: 86%

Functionalization of Carbon Monoxide and tert‐Butyl Nitrile by Intramolecular Proton Transfer in a Bis(Phosphido) Thorium Complex

et al. 2018

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We report intramolecular proton transfer reactions to functionalize carbon monoxide and tert-butyl nitrile from ab is(phosphido) thorium complex. The reaction of (C 5 Me 5 ) 2 Th[PH(Mes)] 2 ,M es = 2,4,6-Me 3 C 6 H 2 ,w ith 1atm of CO yields (C 5 Me 5 ) 2 Th(k 2 -(O,O)-OCH 2 PMes-C(O)PMes),i n which one CO molecule is inserted into each thoriumphosphorus bond. Concomitant transfer of two protons, formerly coordinated to phosphorus,a re nowb ound to one of the carbon atoms from one of the inserted CO molecules. DFT calculations were employed to determine the lowest energy pathway. With tert-butyl nitrile, t BuCN,only one nitrile inserts into at horium-phosphorus bond, but the proton is transferred to nitrogen with one phosphido remaining unperturbed affording (C 5 Me 5 ) 2 Th[PH(Mes)][k 2 -(P,N)-N(H)C-(CMe 3 )P(Mes)].S urprisingly,r eaction of this compound with KN(SiMe 3 ) 2 removes the proton bound to nitrogen, not phosphorus.Carbon monoxide is aC 1 feedstock molecule with relatively inert chemistry owing to the strength of the CO bond. [1] The transformation of non-renewable products,s uch as CO and CO 2 ,i nto starting materials and value-added chemicals is desirable.T his has been accomplished for decades using Fischer-Tropsch chemistry in which CO and H 2 are converted into liquid hydrocarbons. [2] However,t his reaction requires acatalyst as well as elevated temperature and pressure.Thus, novel techniques for hydrogen addition to CO,i ncluding stoichiometric reactions,w ould enhance our knowledge of functionalizing CO into hydrocarbons.Mid-to late-transition metal carbonyl complexes are well known. In contrast, the actinides are large,h ighly electropositive metals with minimal metal-ligand bonding interaction, and their valence orbitals have little need for p-acceptor ligands.T herefore,C Oi sapoor ligand for felements,w ith few examples. [3][4][5][6][7][8][9] However,t hese characteristics make actinides well-suited for small molecule activation of oxygenated substrates. [10,11] While reductive coupling of CO is readily accomplished by low-valent f-element complexes such as U III , [12][13][14][15][16][17][18][19][20] Sm II , [21] and aL a III dinitrogen complex, [22] the most common reaction with CO is migratory insertion and CÀC bond formation. [23][24][25][26][27][28][29][30][31][32] However,t wo reports describe the reductive coupling of CO with U III complexes,a nd have observed proton migration to carbon, but only upon heating. [33,34] Our group has been exploring the unusual reactivity of actinide-phosphorus bonds to exploit hard-soft differences, [35] as well as the weak actinide-phosphorus bond which should be effective for small molecule activation. Thei nsertion of CO into at horium-, scandium, or hafnium-phosphorus bond has been previously reported. [36][37][38][39] Both of these reactions produce h 2 -acyl products.H erein, we report the reactivity of the bis(phosphido) complex, (C 5 Me 5 ) 2 Th[PH(Mes)] 2 , [40] Mes = 2,4,6-Me 3 C 6 H 2 ,w ith CO in which both protons are transferred from ph...

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Lithium‐Aluminate‐Catalyzed Hydrophosphination Applications

et al. 2019

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Synthesized, isolated, and characterized by X-ray crystallography and NMR spectroscopic studies,l ithium phosphidoaluminate iBu 3 AlPPh 2 Li(THF) 3 has been tested as ac atalyst for hydrophosphination of alkynes,a lkenes,a nd carbodiimides.B ased on the collective evidence of stoichiometric reactions,NMR monitoring studies,kinetic analysis,and DFT calculations,amechanism involving deprotonation, alkyne insertion, and protonolysis is proposed for the [iBu 3 AlHLi] 2 aluminate catalyzedh ydrophosphination of alkynes with diphenylphosphine.T his study enhances further the development of transition-metal-free,a tom-economical homogeneous catalysis using common sustainable main-group metals.

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A P–H functionalized Al/P-based frustrated Lewis pair – hydrophosphination of nitriles, ring opening with cyclopropenones and evidence of PC double bond formation

Cited by 24 publications

References 96 publications

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

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

Functionalization of Carbon Monoxide and tert‐Butyl Nitrile by Intramolecular Proton Transfer in a Bis(Phosphido) Thorium Complex

Lithium‐Aluminate‐Catalyzed Hydrophosphination Applications

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