New Ag(I)-Iminophosphorane Coordination Polymers as Efficient Catalysts Precursors for the MW-Assisted Meyer-Schuster Rearrangement of Propargylic Alcohols in Water

Treatment of the N-thiophosphorylated iminophosphorane ligands (PTA)=NP(=S)(OR)(2) [PTA = 1,3,5-triaza-7-phosphaadamantane, 3a and 3b] and (DAPTA)=NP(=S)(OR)(2) [DAPTA = 3,7-diacetyl-1,3,7-triaza-5-bicyclo[3.3.1]nonane, 4a and 4b] with an equimolecular amount of AgSbF6 leads to high-yield formation of the new one-dimensional coordination polymers [Ag{mu(2)-N,S-(PTA)=NP(=S)(OR)(2)}](x)[SbF6](x) (5a and 5b) and [Ag{mu(2)-O,S(DAPTA)=NP(=S)(OR)(2)}](x)[SbF6](x) (6a and 6b), respectively. These new (iminophosphorane)silver(I) coordination polymers are efficient catalyst precursors for the Meyer-Schuster isomerization of both terminal and internal alkynols. Reactions proceeded in water, under aerobic conditions and using microwave irradiation as heating source, to afford the corresponding alpha,beta-unsaturated carbonyl compounds in excellent yields, without the addition of any cocatalyst. Remarkably, it should be noted that this catalytic system can be recycled up to 10 consecutive runs (1st cycle 45 min, 99%; 10th cycle 6 h, 97%). ESI-MS analysis of 5a in water has been carried out providing valuable insight into the monomeric active species responsible for catalytic activity in water.