A Phosphorus Analogue of p‐Quinodimethane with a Planar P₄ Ring: A Metal‐Free Diphosphorus Source

Abstract

Para-quinodimethane (pQDM) is af undamental structural component in many p-conjugated organic molecules andm aterials. The incorporation of phosphorus atom into p-conjugated frameworks offersu nique opportunitiesf or controlling the properties of derived species. A phosphorus analogueo fp-quinodimethane (pQDM), (IPrC) 2 P 4 [5,I Pr = C{N(Ar)CH 2 } 2 ;A r= 2,6-iPr 2 C 6 H 3 ]f eaturinga planar P 4 ring, was readily accessible by KC 8 -reduction of (IPrC)(PCl 2 ) 2 (2). Base-mediatedC ÀHf unctionalizationo f IPrCH 2 (1)w ith PCl 3 afforded 2.T he formation of 5 was expected to occur through ad imerization of the transient 3H-diphosphirene (IPrC)P 2 (4), which was theoretically suggested to have an intermediate diradical character.C ompound 5 underwentp hoto-induced ring-contraction reaction to form the singlet diradicaloid (IPrCP) 2 VI and white phosphorus (P 4 ). Thef ormationo fa nd VI andP 4 suggested the formald iphosphorus( P 2 )e limination from 5.

An investigation of targeted inhibition of transcription factor activity with pyrrole imidazole polyamide (PA) in chronic myeloid leukemia (CML) blast crisis cells

“…For more in-depth structural information concerning how hairpin polyamides bind to a target sequence, please refer to [12,13]. It may be presumed that a PA, with a short half-life, binds and inhibits TF activity within 24 hours in culture whereas the biological consequences of altered transcription may lag behind.…”

Diphosphorus Release and Heterocumulene Oligomerisation by Nickel Complexes

“…[11] Recently, the group of Ghadwal showed that P 2 [6,9,11] units are released upon reaction of a phosphorus analogue of p-quinodimethane [(IPr=C) 2 P 4 ] (IPr = 1,3-bis(2,6-di-isopropylphenyl)imidazolin-2-ylidene) containing a planar P 4 ring with cyclohexadiene. [12] However, this reaction was not selective, affording both P 4 and the cycloaddition product B.…”

“…Under mild thermal activation, D releases P 2 which could be detected by molecular beam mass spectrometry and ultimately transforms to red phosphorus [11] . Recently, the group of Ghadwal showed that P 2 units are released upon reaction of a phosphorus analogue of p ‐quinodimethane [(IPr=C) 2 P 4 ] (IPr=1,3‐bis(2,6‐di‐ iso ‐propylphenyl)imidazolin‐2‐ylidene) containing a planar P 4 ring with cyclohexadiene [12] . However, this reaction was not selective, affording both P 4 and the cycloaddition product B .…”

Heterocyclopentanediyls vs Heterocyclopentadienes: A Question of Silyl Group Migration

“…Sterically demanding substituents further provide kinetic protection, rendering the isolation of such species possible (Scheme ). − In particular, our own group could demonstrate the versatile reactivity of the stable four-membered cyclic biradical [P­(μ-NR)] 2 ( 1 , R = Ter [2,6-dimesitylphenyl] or Hyp [tris­(trimethylsilyl)­silyl]), which is based solely on group 15 elements (Scheme ). − …”