Facile Synthesis of Dibenzo-7λ³-phosphanorbornadiene Derivatives Using Magnesium Anthracene

Abstract

Unprotected dibenzo-7λ(3)-phosphanorbornadiene derivatives RPA (A = C(14)H(10) or anthracene; R = (t)Bu, dbabh = NA, HMDS = (Me(3)Si)(2)N, (i)Pr(2)N) are synthesized by treatment of the corresponding phosphorus dichloride RPCl(2) with MgA·3THF, in cold THF (~20% to 30% isolated yields). Anthracene and the corresponding cyclic phosphane (RP)(n) form as coproducts. Characteristic NMR features of the RPA derivatives include a doublet near 4 ppm in their (1)H NMR spectra and a triplet peak in the 175-212 ppm region of the (31)P NMR spectrum ((2)J(PH) ~14 Hz). The X-ray structures of the AN-PA and (HMDS)PA derivatives are discussed. Thermolysis of RPA benzene-d(6) solutions leads to anthracene extrusion. This process has a unimolecular kinetic profile for the (i)Pr(2)NPA derivative. The 7-phosphanorbornene anti-(i)Pr(2)NP(C(6)H(8)) could be synthesized (70% isolated yield) by thermolysis of (i)Pr(2)NPA in 1,3-cyclohexadiene.

A “masked” source for the phosphaalkene MesP=CH2: Trapping, rearrangement, and oligomerization

“…An alternative strategy to “mask” a phosphinidene is illustrated by azaphosphirine E in which the by‐product is a nitrile . Recently, a convenient route to “masked” phosphinidenes of type F was reported starting with the conveniently generated magnesium anthracenide, MgA·3THF . This one‐step methodology is also amenable to the preparation of “masked” digermene G …”

Facile Phenylphosphinidene Transfer Reactions from Carbene–Phosphinidene Zinc Complexes

“…[3] Cummins and co-workers developed the unprotected dibenzo-7l 3 -phosphanorbornadiene A as as ource of the transient [iPr 2 NP],w hich undergoes a[ 1 + +4]-cycloaddition with 1,3-cyclohexadiene. [4] Driess and co-workers successfully transferred the parent phosphinidene [HP] from phosphasilene B (Dipp = 2, 6-diisopropylphenyl) to an Nheterocyclic carbene, [5] and Weber et al demonstrated the acycliccarbene-phosphinidene adducts C (R = tBu, Cy,1-Ad, Ph, Mes) to be viable [RP] transfer agents to diphenylketene. [6] Interestingly,A rduengo and co-workers showed that the Lewis acid BPh 3 induces formation of cyclopolyphosphines (PPh) n (n = 3-5) from Mes NHC = PPh D, [7] but no transfer reactions of the extruded phenylphosphinidene moiety have been reported to date.T his inspired us to target the sterically little encumbered Me NHC = PPh (1; Scheme 1) and study its ability to transfer [PhP] to suitable substrates in the presence of an appropriate Lewis acid.…”

Synthesis, Characterization, and Thermolysis of Dibenzo-7-dimethylgermanorbornadiene

“…Assembling 7-heteroatom-norbornadiene architectures via the salt metathesis reaction of an anthracenide salt and a maingroup halide reaction partner is precedented for silicon, 2,3 tin, 4,5 and more recently phosphorus, 6 yet Me 2 GeA has not been previously reported in the literature. In 1980 Neumann was first to report the synthesis of a 7-germanorbornadiene and established that such species are thermal precursors to germylene (Me 2 Ge), the heavier analogue of a carbene.…”

“…11 These results mirror our previous observation that PhPCl 2 and PCl 3 do not give rise to the corresponding 7-phosphanorbornadiene derivatives on treatment with MgA·3THF. 6,12 Probing the thermal stability and chemical behavior toward retro Diels−Alder chemistry, a solution of Me 2 GeA in toluene was heated for ca. 16 crude mixture indicated the formation of anthracene and (Me 2 Ge) 2 A, which after removal of anthracene using a charcoal plug was isolated as a pure substance in 71% yield (based on germanium).…”

“…6,14 X-ray-quality crystals of Me 2 GeA and (Me 2 Ge) 2 A were grown from saturated solutions in diethyl ether (see Figures 1 and 2 and X-ray Diffraction Studies in the Supporting Information). Of approximate C 2v symmetry, the two structures feature a strained architecture at the germanium centers, with a C13−Ge−C14 angle of 77.72(5)°in Me 2 GeA and a C13− Ge2−Ge1 angle of 95.53(3)°in (Me 2 Ge) 2 A, respectively.…”