Revisiting the Phospha-Wittig–Horner Reaction

A novel access to phosphanylidene-phosphorane complexes via P-donor substitution and a detailed bonding analysis

Phospha-Wittig reagents such as phosphanylidene-phosphoranes and their transition metal complexes are of great interest as sources of P1 building blocks but the access is still limited. Herein, we describe a new access to phosphanylidene-phosphorane complexes starting from the N-methylimidazole-to-phosphinidene complex adduct. The complexes were studied electrochemically and theoretically, also with respect to their 31P NMR data, and the P-P bonds were evaluated by various DFT-derived descriptors.

Diels-Alder reactions of 1-phosphabutadienes: a highly selective route to P[double bond, length as m-dash]C-substituted phosphacyclohexenes

Kinetically stabilized 1-phosphahaloprenes (2-halo-1-phosphabutadienes) as well as 1-phosphaisoprene undergo a hitherto unknown phospha-Diels-Alder dimerization of the P[double bond, length as m-dash]C-C[double bond, length as m-dash]C units upon heating. The [4+2] cyclodimerization is highly stereo- and regio-selective. The phosphaalkene-substituted phosphacyclohexene product is an unprecedented P(sp²),P(sp³) ligand that is of interest in polymer/materials science and catalysis.

Organocatalytic, Chemoselective Hydrophosphenylation/oxa-Michael Addition Cascade toward Diastereo- and Enantioenriched 1,3-Dihydroisobenzofuryl Phosphonates

An efficient method for the construction of chiral C-P bond via an enantioselective 1,2-hydrophosphenylation followed by an oxa-Michael addition cascade of ortho-formyl chalcones has been developed. This provides the diastereoenriched ( cis)-1,3-dihydroisobenzofuryl phosphonates with excellent enantioselectivities (up to >99%). The origin of enantio- and diastereoselectivity is induced by using a chiral bifunctional organocatalyst. Further, functionalization to highly enantioselective 3-substituted phthalides has also been demonstrated.

Sequential Electrophilic Substitution Reactions of Tungsten-Coordinated Phosphenium Ions and Phosphine Triflates

ion of chloride from [W(CO)₅{PPhCl₂}] with AgOSO₂CF₃ leads to the phosphine triflate complex [W(CO)₅{PPhCl(OSO₂CF₃)}] which undergoes electrophilic substitution reactions with N,N-diethylaniline, anisole, N,N-dimethyl-p-toluidine, toluene, biphenyl, naphthalene, 2,7,9,9-tetramethyl xanthene, and allyltrimethylsilane to form the chlorophosphine complexes [W(CO)₅{PPhClR}], where R = p-diethylanilinyl, p-anisyl, 2-(N,N-dimethyl-4-methylphenyl), p-tolyl, p-phenylphenyl, 1-naphthyl, 4-(2,7,9,9-tetramethylxanthyl), and allyl. Abstraction of the second chloride with AgOSO₂CF₃ leads, in most cases, to the respective phosphine triflates [W(CO)₅{PPhR(OSO₂CF₃)}], which react with ferrocene to form the ferrocenyl phosphine complexes [W(CO)₅{PPhR(C₁₀H₉Fe)}]. The W(CO)₅ unit can be removed via photolysis in the presence of bis(diphenylphosphino)ethane to form metal-free phosphines.

Insertion of phosphinidene complexes into the P-H bond of secondary phosphine oxides: a new version of the phospha-Wittig synthesis of P=C double bonds

Terminal phosphinidene complexes [RP-W(CO)5], as generated at 60 °C in the presence of copper chloride from the appropriate 7-phosphanorbornadiene complexes, react with secondary phosphine oxides Ar2P(O)H to give the insertion products into the P-H bonds. After metalation with NaH, these products react with aldehydes to give the corresponding phosphaalkenes which are trapped by dimethylbutadiene.

Synthesis and solid-state structures of gold(i) complexes of diphosphines

A series of diphosphine bis(gold) complexes were synthesised and the importance of aurophilic interactions for their structure formation was studied.

Synthesis of the first metal-free phosphanylphosphonate and its use in the “phospha–Wittig–Horner” reaction

The synthesis of the first phophanylphosphonate, Mes*PH–PO(OEt)₂ (2-H), in which the P(iii) centre is not coordinated by a metal fragment is reported.