Covalently Bonded Bis(phosphane)gold(I) Cations in a Cross‐Linked Phosphazene Polymeric Matrix as Recyclable Supported Catalysts for Thermal and Microwave‐Assisted Hydration of Alkynes

Abstract

The unexpected finding that the complex [Au(PPh3)2]PF6 (C1) catalyses the specific hydration of 1‐octyne, (p‐phenoxyphenyl)acetylene, phenylacetylene, (p‐chlorophenyl)acetylene and benzylacetylene at 100 °C in the presence of H2SO4 and THF or methanol as solvents, specially using microwave radiation, led to the first gold(I) recyclable catalysts for this reaction. The phosphazene polymeric framework of idealised formula {[NP(O2C12H8)]0.85[NP(OC6H4PPh2)2 (AuPF6)0.5]0.15}n (C2), and the newly synthesised cyclomatrix material of idealised formula {[N3P3(OC6H4PPh2)6](AuPF6)3.5}n (C3), both having cationic [–Ph2P–Au+–PPh2–] cross‐linking sites, catalysed the complete hydration of terminal alkynes at 100 °C and 150 °C and could be used six and four times respectively without significant loss of activity. The mechanism of the catalytic system is based on the initial reversible displacement of one anchoring O–C6H5–PPh2 group from the [–Ph2P–Au+–PPh2–] cross‐linking sites by an alkyne molecule. Using microwave radiation, the hydration of (p‐phenoxyphenyl)acetylene, phenylacetylene, (p‐chlorophenyl)acetylene and benzylacetylene can be completed in 5 min to 2 h in the absence of any gold(I) catalyst.

Polyphosphazenes for the Stille reaction: a new type of recyclable stannyl reagent

“…13 C{ 1 H} NMR (CDCl3, 100.613 MHz), δ (ppm): 131.5, 130. 7,129.4,127.4 (b,CPh),33.9,32.7,30.7,30.3,28.3,28.0,23.2,21.9 (b,CH2,. Mn = 16476 D; Mw/Mn = 1.2.…”

“…13 C{ 1 H} NMR (CDCl3, 100.613 MHz), ), δ (ppm):148. 7,132.3,130.9,129.2,128.7,125.0,122.8 (b,CPh,C12H8O2),34.0,33.8,32,4,31.6,29.8,27.8,22.7,14.4 (b,CH2,. Mn = 63500; Mw/Mn = 1.13.…”

Phosphine functionalized polyphosphazenes: soluble and re-usable polymeric reagents for highly efficient halogenations under Appel conditions

“…The unusually high flexibility of the chemical backbone [28] and thus conformational flexibility further makes them ideally suited as solution state polymeric reagents in organic synthesis. Furthermore, the potential for chirality [29][30][31] renders them highly interesting as polymer supports [32][33][34][35].…”

Efficient [(NHC)Au(NTf2)]-catalyzed hydrohydrazidation of terminal and internal alkynes

“…Cationic gold complexes with weakly coordinating counterions (which are often considered to be solvent-separated ions) [1][2][3], render powerful catalysts for the transformation of organic substrates [4][5][6], specifically the reactions of alkynes with a variety of heteroatom nucleophiles (Scheme 1) [7] such as water or alcohol [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22], primary or secondary amines [23][24][25][26][27][28], or hydrazine [29][30][31]. These reactions are synthetically useful since gold catalysis is characterized by a good functional group tolerance for oxygen and nitrogen-containing molecules, which tend to be more difficult for catalytic transformations utilizing other transition metals [32][33][34][35][36].…”