When Sterics Overcome Electronics: An Unusual Haptotropic P→N Pentacarbonyltungsten Shift

Helten, Holger; Schnakenburg, Gregor; Daniels, Jörg; Arduengo, Anthony J.; Streubel, Rainer

doi:10.1021/om1007709

Cited by 6 publications

(5 citation statements)

References 88 publications

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“…Thus, the CR 2 – O motif was replaced by a CR= N ‐bonded ferrocenyl unit. This imino phosphate motif (type G molecule, Scheme ) has rarely been described, especially in ferrocene chemistry, where a sole C=N–P(O)Ph 2 unit has been reported, however, without its synthetic procedure , …”

Section: Resultsmentioning

confidence: 99%

(Planar‐Chiral) Ferrocenylmethanols: From Anionic Homo Phospho‐Fries Rearrangements to α‐Ferrocenyl Carbenium Ions

2017

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The reaction of FcCH2OH with chlorophosphates gave ferrocenyl phosphates FcCH2OP(O)(OR)2 [Fc = Fe(η5‐C5H5)(η4‐C5H4)], which readily separate into phosphate anions and ferrocenyl carbo‐cations. The latter species undergoes consecutive reactions, for example, electrophilic aromatic substitutions. When nitriles, instead of alcohols, are treated with FcLi or tBuLi and chlorophosphates, chiral‐pool based ferrocenylimino phosphoramidates Fc‐CR=N‐P(O)(OR*)2 are formed, which are promising candidates for anionic homo phospho‐Fries rearrangements. Moreover, the sterically demanding chiral chlorophosphate with R* enabled oxidative couplings of the imines to form a diferrocenylazine. Similarly, the reaction of Fc–Li with 9‐anthrylnitrile produced a 10‐ferrocenyl‐substituted product, contrary to a reaction at the C≡N functionality. A planar‐chiral ortho‐P(S)Ph2‐functionalized ferrocenylmethanol also gave carbo‐cations under acidic conditions. These species can be sulfurized in a unique way giving thio ethers, whereby the in situ formed 1,2‐P(S)Ph2,CH2+ ferrocene cation acts as the sulfur and electron source. However, lowering the substrate concentration prevents sulfur migration, resulting in electrophilic substitution reactions with aromatic solvents. Planar‐chiral ferrocenylmethyl thio or anisyl derivatives were applied as ligands in Pd‐catalyzed Suzuki–Miyaura C,C cross‐couplings for the atroposelective synthesis of hindered biaryls with up to 26 % ee at low catalyst loadings (1 mol‐% Pd).

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Section: Resultsmentioning

confidence: 99%

(Planar‐Chiral) Ferrocenylmethanols: From Anionic Homo Phospho‐Fries Rearrangements to α‐Ferrocenyl Carbenium Ions

2017

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“…www.eurjic.org col. [26] The NMR spectroscopic data of complex 13 (δ = 33.2 ppm, 1 J W,P = 227.6 Hz, 1 J P,H = 300.1 Hz) are similar to those of the known complex [Li (12-crown-4)][(CO) 5 WRP(H) O] (δ = 46.0 ppm, 1 J W,P = 244.1 Hz, 1 J P,H = 302.6 Hz), [14] but has a solvent-separated ion-pair structure.…”

Section: Resultsmentioning

confidence: 99%

“…As complex 13 possesses a P ‐CH 3 substituent instead of the P ‐CH(SiMe 3 ) 2 , it must have been formed by a desilylation pathway, which is still unknown. Recently, a selective desilylation of this particular substituent was achieved in the case of a diazaphosphole complex by a different protocol 26. The NMR spectroscopic data of complex 13 ( δ = 33.2 ppm, 1 J W,P = 227.6 Hz, 1 J P,H = 300.1 Hz) are similar to those of the known complex [Li(12‐crown‐4)][(CO) 5 WRP(H)O] ( δ = 46.0 ppm, 1 J W,P = 244.1 Hz, 1 J P,H = 302.6 Hz),14 but has a solvent‐separated ion‐pair structure.…”

Section: Resultsmentioning

confidence: 99%

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P‐OR Functional Phosphanido and/or Li/OR Phosphinidenoid Complexes?

Duan¹,

Schnakenburg²,

Daniels³

et al. 2012

Eur J Inorg Chem

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Keywords: Phosphanes / P ligands / Lithium / Phosphinidenoids / Tungsten / Structure elucidation P-H,P-OR-substituted phosphane complexes 3a-e have been synthesized by two methods: (1) the thermal reaction of 2Hazaphosphirene complex 1 with methanol, n-butanol, or ethylene glycol monomethyl ether (3b,c,e) or (2) the reaction of P-chlorophosphane complex 2 with appropriate sodium phenolate salts (3a,d). All the complexes 3a-e were obtained in good yields and fully characterized by NMR, IR, MS, and elemental analysis. Furthermore, the structures of 3a, 3d and 3e were confirmed unambiguously by X-ray analysis. The de-

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“…Zero point corrections and thermal corrections to free energies were adopted from frequencies calculations on the optimization level (RI‐BP86/def2‐SV(P), COSMO). The practicability of this approach has been demonstrated before 61…”

Section: Methodsmentioning

confidence: 99%

“Spontaneous” Ambient Temperature Dehydrocoupling of Aromatic Amine–Boranes

Helten

Robertson

Staubitz

et al. 2012

Chemistry A European J

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The dehydrocoupling/dehydrogenation behavior of primary arylamine-borane adducts ArNH(2)⋅BH(3) (3 a-c; Ar = a: Ph, b: p-MeOC(6)H(4), c: p-CF(3)C(6)H(4)) has been studied in detail both in solution at ambient temperature as well as in the solid state at ambient or elevated temperatures. The presence of a metal catalyst was found to be unnecessary for the release of H(2). From reactions of 3 a,b in concentrated solutions in THF at 22 °C over 24 h cyclotriborazanes (ArNH-BH(2))(3) (7 a,b) were isolated as THF adducts, 7 a,b⋅THF, or solvent-free 7 a, which could not be obtained via heating of 3 a-c in the melt. The μ-(anilino)diborane [H(2)B(μ-PhNH)(μ-H)BH(2)] (4 a) was observed in the reaction of 3 a with BH(3)⋅THF and was characterized in situ. The reaction of 3 a with PhNH(2) (2 a) was found to provide a new, convenient method for the preparation of dianilinoborane (PhNH)(2)BH (5 a), which has potential generality. This observation, together with further studies of reactions of 4 a, 5 a, and 7 a,b, provided insight into the mechanism of the catalyst-free ambient temperature dehydrocoupling of 3 a-c in solution. For example, the reaction of 4 a with 5 a yields 6 a and 7 a. It was found that borazines (ArN-BH)(3) (6 a-c) are not simply formed via dehydrogenation of cyclotriborazanes 7 a-c in solution. The transformation of 7 a to 6 a is slowly induced by 5 a and proceeds via regeneration of 3 a. The adducts 3 a-c also underwent rapid dehydrocoupling in the solid state at elevated temperatures and even very slowly at ambient temperature. From aniline-borane derivative 3 c, the linear iminoborane oligomer (p-CF(3)C(6)H(4))N[BH-NH(p-CF(3)C(6)H(4))](2) (11) was obtained. The single-crystal X-ray structures of 3 a-c, 5 a, 7 a, 7 b⋅THF, and 11 are discussed.

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When Sterics Overcome Electronics: An Unusual Haptotropic P→N Pentacarbonyltungsten Shift

Cited by 6 publications

References 88 publications

(Planar‐Chiral) Ferrocenylmethanols: From Anionic Homo Phospho‐Fries Rearrangements to α‐Ferrocenyl Carbenium Ions

(Planar‐Chiral) Ferrocenylmethanols: From Anionic Homo Phospho‐Fries Rearrangements to α‐Ferrocenyl Carbenium Ions

P‐OR Functional Phosphanido and/or Li/OR Phosphinidenoid Complexes?

“Spontaneous” Ambient Temperature Dehydrocoupling of Aromatic Amine–Boranes

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