2,3-Benzo-7-phosphanorbornadiene Complexes: Synthesis and Chemistry

Abstract

The reaction of benzyne with 3,4-dimethylphosphole pentacarbonylmolybdenum complexes affords the corresponding 2,3-benzo-7-phosphanorbornadiene complexes through [4+2] cycloaddition. The condensation takes place on the less hindered side of the phosphole ring corresponding to the phosphorus substituent as shown by the X-ray crystal structure analysis of the phenyl derivative (2). The strain at the bridge of 2 (C−P−C angle ca. 80°) induces a variety of splitting reactions. Upon decomplexation by dppe at 110 °C in toluene, phenylphosphinidene is generated and recovered as phenylphosphine. Upon sulfurization under the same conditions, [PhPS2] is formed and trapped as a [4+2] adduct with 2,3-dimethylbutadiene. Potassium tert-butylate attacks the bridge in THF at −78 °C and, after methylation and hydrolytic workup, yields [Ph(Me)P(OH)Mo(CO)5].

Recent advances in organophosphorus–chalcogen and organophosphorus–pincer based macrocyclic compounds and their metal complexes

“…Perspective conformers, each of the rac and meso isomers, were crystallized. Monocoordinated phosphinidenes (A, Chart 1) [74][75][76][77] are often regarded as phosphorus analogues of carbenes having a neutral P I center, whereas phosphinidene chalcogenides (R-PvE; B, Chart 1) [78][79][80][81] are the oxidized form of phosphinidenes (P I → P III ). In the recent past, phosphinidene chalcogenides (R-PvE) have been employed in transition metal chemistry, [82][83][84] cycloaddition reactions, designing many unique phosphine ligands, 85,86 and also in the construction of larger [RPE] n rings (D and E, Chart 1).…”

Hetero Diels–Alder Reactions of Masked Dienes Containing Heavy Group 15 Elements

“…[25] In contrast, structurally characterized compounds containing heavier Group 15 elements (even those not annulated to ab enzene ring), either at the bridgehead or any other position( Figure 5B)o rt heir complexes with transition metals are known only for phosphorus. [26] Furthermore, compounds 7 and 8 contain an extra pnictogen atom, that is, antimony at the bridgehead position. Considering such diaza analogues ( Figure 5A), to the best of our knowledge,n oe xample has yet been structurally characterized, [27] although these compounds have been considered as intermediates in the synthesis of substitutedq uinolines.…”

Trapping Rare and Elusive Phosphinidene Chalcogenides

“…Phosphinidene chalcogenides (R−P=Ch; 2Ch ) are oxidized versions of phosphinidenes (P I →P III ). Despite formally containing a lone pair of electrons at phosphorus, where one would expect an imposition of carbene‐like behavior, olefinic reactivity remains dominant . The presence of phosphinidene sulfides (R−P=S) in solution has been verified using Diels–Alder chemistry, trapping R−P=S with dimethylbutadiene .…”

“…Despite formally containing a lone pair of electrons at phosphorus, where one would expect an imposition of carbene‐like behavior, olefinic reactivity remains dominant . The presence of phosphinidene sulfides (R−P=S) in solution has been verified using Diels–Alder chemistry, trapping R−P=S with dimethylbutadiene . Although this is elegant work demonstrating the resilience of R−P=S, the outcome of the reaction precludes a close examination of the P=S functional group with phosphorus in the +3 oxidation state.…”