Enantiomerically Pure Phosphaalkene–Oxazolines (PhAk‐Ox): Synthesis, Scope and Copolymerization with Styrene

Abstract

The design of a synthetic route to a class of enantiomerically pure phosphaalkene-oxazolines (PhAk-Ox) is presented. The condensation of a lithium silylphosphide and a ketone (the phospha-Peterson reaction) was used as the P=C bond-forming step. Attempted condensation of PhC(=O)Ox (Ox = CNOCH(iPr)CH(2)) and MesP(SiMe(3))Li gave the unusual heterocycle (MesP)(2)C(Ph)=CN-(S)-CH(iPr)CH(2)O (3). However, PhAk-Ox (S,E)-MesP=C(Ph)CMe(2)Ox (1 a) was successfully prepared by treating MesP(SiMe(3))Li with PhC(=O)CMe(2)Ox (52 %). To demonstrate the modularity and tunability of the phospha-Peterson synthesis several other phosphaalkene-oxazolines were prepared in an analogous manner to 1 a: TripP=C(Ph)CMe(2)Ox (1 b; Trip = 2,4,6-triisopropylphenyl), 2-iPrC(6)H(4)P=C(Ph)CMe(2)Ox (1 c), 2-tBuC(6)H(4)P=C(Ph)CMe(2)Ox (1 d), MesP=C(4-MeOC(6)H(4))CMe(2)Ox (1 e), MesP=C(Ph)C(CH(2))(4)Ox (1 f), and MesP=C(3,5-(CF(3))(2)C(6)H(3))C(CH(2))(4)Ox (1 g). To evaluate the PhAk-Ox compounds as prospective precursors to chiral phosphine polymers, monomer 1 a and styrene were subjected to radical-initiated copolymerization conditions to afford [{MesPC(Ph)(CMe(2)Ox)}(x){CH(2)CHPh}(y)](n) (9 a: x = 0.13n, y = 0.87n; GPC: M(w) = 7400 g mol(-1) , PDI = 1.15).

Bis(imino)phosphanes: Synthesis and Coordination Chemistry

“…Not only do they show a Δ G preference for the E,E- ion over its E­(P),Z­(N)- and E­(N),Z­(P) -isomers of 9.0 and 11.4 kcal·mol –1 , respectively, they also reveal it to be favored by a significant 7.8 kcal·mol –1 over its N,P,N-isomeric precursor E,E - 4e . Subsequent treatment of the solution with NEt 3 to deprotonate the ion furnished the unique 1,3,5-phosphadiazapentadiene E,E - 9 (δ 31 P 188.9; the E,E -isomer is favored over the E­(P),Z­(N) and ( E­(N),Z­(P) by 2.1 and 2.4 kcal·mol –1 , respectively). The DFT calculations show that E,E - 9 is thermodynamically favored over the N,P,N-isomeric bis­(imino)­phosphane ( 5e ) by a substantial Δ G of 10.1 kcal·mol –1 .…”

Phosphorus-containing polymers from tetrakis-(hydroxymethyl)phosphonium sulfateiii. A new hydrolysis-resistant tris(allyloxymethyl)phosphine oxide and its thiol-ene reaction under ultraviolet irradiation

“…17 Whereas, poly(phosphine oxide)s show excellent resistant to hydrolysis because this kind of polymer is formed though P-C bond linkages. [23][24][25][26] In recent years, phosphorus-carbon bonds containing monomers and polymers have been the subject of extensive research. [27][28][29][30][31] In this article, a convenient method to prepare crosslinked poly(phosphine oxide) by the aid of thiol-ene reaction is proposed for the rst time.…”

Synthesis of a novel azaphosphorine flame retardant and its application in epoxy resins

“…However, most phosphorus‐containing flame retardants still have many shortcomings in polymer modification; these include migration, leaching, and long‐term hydrolytic instability . It has been reported that azaphosphorine, which contains PCN bond, possesses an outstanding thermal stability and excellent solvent resistance . Also, this type of flame retardant can promote char formation and improve the flame retardancy of EPs at a low phosphorus content.…”