Facile synthesis of luminescent benzo-1,2-dihydrophosphinines from a phosphaalkene

Abstract

The addition of 4-trifluoromethyl-1-ethynylbenzene, phenylacetylene, or 4-ethynylanisole to P-mesityldiphenylmethylenephosphine, 1, produced photoluminescent 1,2-dihydrophosphinines 4a-c, respectively, in quantitative yield via a [4 + 2] cycloaddition. Limited reactivity was observed between 1 and non-aromatic alkynes. P-[Bis(trimethylsilyl)amino][(trimethylsilyl)methylene]phosphine, 2, and P-mesityl[(t-butyl)(trimethylsiloxy)methylene]phosphine, 3, showed extremely limited reactivity with all alkynes examined. The reactivity of phosphaalkenes toward terminal alkynes is compared to that of alkenes as well as silenes and germenes.

Oxophosphonium-alkyne cycloaddition reactions: reversible formation of 1,2-oxaphosphetes and six-membered phosphorus heterocycles

“…Our computational results indicate that the acyclic 1-phospha-4-oxa-butadiene state of [ 2a ] + is thermally accessible, which prompted us to investigate whether it can be trapped by [4 + 2] hetero Diels–Alder cycloaddition reactions. Similar to α,β-unsaturated carbonyls, which are important dienes in hetero Diels–Alder reactions for material and natural product synthesis, phospha-butadiene derivatives have been used in cycloaddition reactions for the construction of phosphorus-containing heterocycles. − Furthermore, neutral σ 3 λ 5 -phosphoranes containing the PC–­CO system were postulated as reactive intermediates based on their ability to undergo [4 + 2] cycloaddition reactions with polar multiple bonds. , …”

A Convenient Synthesis of 1,2,4‐ and 1,3,4‐Azadiphospholes

“…[4][5][6][7] Another remarkable recent achievementi st he activationo fd ihydrogen by 2,4,6-tri-tert-butyl-1,3,5-triphosphabenzene,w hich proceeds withoutt ransitionm etals. [8] Moreover, p-conjugated six-membered phosphorus heterocycles [9][10][11] as well as non-aromatic five-membered rings, such as phospholesa nd their derivatives (e.g.,o xides, sulfides, transition metal complexes), are being extensively investigated as precursors or components of optoelectronic materials,s uch as organicl ight-emitting diodes, organic semiconductors, and organic solar cells. [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] Azadiphospholes [28] are aromatic and electron-rich heterocycles, [29,30] which eventually may find applications in organic electronic materials, for example, as electron donors (n-dopants).…”

“…Another remarkable recent achievement is the activation of dihydrogen by 2,4,6‐tri‐ tert ‐butyl‐1,3,5‐triphosphabenzene, which proceeds without transition metals . Moreover, π‐conjugated six‐membered phosphorus heterocycles as well as non‐aromatic five‐membered rings, such as phospholes and their derivatives (e.g., oxides, sulfides, transition metal complexes), are being extensively investigated as precursors or components of optoelectronic materials, such as organic light‐emitting diodes, organic semiconductors, and organic solar cells …”

Thiophosphonium–Alkyne Cycloaddition Reactions: A Heavy Congener of the Carbonyl–Alkyne Metathesis

“…The heavy atom α,β-unsaturated ketones contain reactive double bonds and thus provide a platform for rich follow-up chemistry. Phosphabutadiene derivatives have been extensively used in cycloaddition reactions for the construction of phosphorus-containing heterocycles, − and many examples of P=C–C=O compounds reacting in hetero-Diels–Alder reactions were reported. , Since the analogous reactivity with a P=C–C=S moiety is unexplored, we attempted to identify substituent effects that would stabilize this acyclic structure. The rather low transition state with ethoxyacetylene indicates that electron-donating groups might be beneficial in this respect.…”