Rearrangements tetrakis palladium

Substitution reactions of allylic nitro compounds often lead to rearranged products, as in palladium(0)-catalysed aminations and alkylations. Thus treatment of the nitro ester 419 with piperidine in the presence of tetrakis(triphenylphosphine)palladium yields a mixture of the unrearranged and rearranged amines 420 (R = piperidin-l-yl) and 421... 

N Claisen rearrangement.3 This Pd(II) salt permits the rearrangement of S- llylthioimidates to N-allylthioamides. Tetrakis(triphcnylphosphine)palladium and various other metal salts are inactive. The rearrangement is inhibited by a substituent til the 2-position of the allyl group. 

In the presence of tetrakis(triphenylphosphine)palladium a-cyano allylic acetates rearrange to y-acetoxy-a,/3-unsaturated nitriles. The products can he converted into furanc derivatives (equation II).2... 

Allyloxypyrimidine largely resists rearrangement even at 200 C. However, allylic cyclopentenyl 2-pyrimidinyl ethers 879 can be rearranged on catalysis by tetrakis(tri-isopropyl phosphite)palladium (Scheme 95). 

In 1995 Pyne and Dong95 found that the ally lie sulfoximine 165 underwent a facile and completely regioselective and efficient rearrangement to the allylic sulfinamide 166 in the presence of tetrakis(triphenylphosphine)palladium(0) ((PPh3)4Pd) catalyst (5 mol%) at room temperature. Mild base hydrolysis of the reaction mixture (10% aqueous sodium hydroxide/methanol, 1 10, room temperature, 2 h) gave pure sulfonamide 167 after purification by column chromatography (silica gel) in 90% overall yield. 

Complex 4 slowly reacts to give 5 in the solid state and can be crystallized from a toluene solution by addition of pentane. The coordination of the double bond was detected by inspection of the Pt-H and P-H coupling constants in the HNMR spectrum of 4. The reactivity of 4 dilfers from that of uncomplexed 3 in that the rearrangement to 5 is faster than the intended reactions of some reagents with the ligand. Coordination and insertion reactions were not observed with tetrakis(triphenylphosphane)palladium(0). 

A related tetrakis(triphenylphosphino)palladium catalyzed aza-Claisen rearrangement is described in ref 134. For another example of 1.4-asymmetric induction in aza-Claisen rearrangements see ref 122. 

The 2-bromododeca-l,ll-dien-6-yne derivative 461 undergoes a triple cyclization, followed by rearrangement, under the influence of a palladium catalyst to yield 462. Cross-coupling of the iodo compound 463 with ( )-l-hexen-l-ylzinc chloride in the presence of tetrakis(triphenylphosphine)palladium yields 68% of the indane 464 and 19% of the uncyclized product 465 ". ... 

Transition-metal induced [1,2]-rearrangement is also available to obtain phosphaalkyne 39. Dichlorophosphaethene 2a was allowed to react with an equivalent amount of tetrakis(triphenylphosphine)palladium(0) to afford phosphaalkyne 39 through intermediates (Scheme 21) [37]. The rearrangement process takes place in the reaction of dibromophosphaethene 2b with a small amount (0.2 equiv.) of dibromobis(triphenylphosphine)nickel(II) in the presence of zinc and tetraethylammonium iodide through the generation of a nick-el(0) intermediate [38]. Complex 43 was isolated in the reaction of 2a and tetrakis(triethylphosphine)platinum(0) which could afford phosphaalkyne 39 [27,28,39]. 

Three types (A-C) of rearrangement of 1,3-diene epoxides are realized by a catalytic amount of tetrakis(triphenylphosphine)palladium(0) in dichloromethane, benzene, or ethereal solvents (Scheme 1). The course of the Pd(0)-catalyzed reaction of the epoxides appeared to be highly dependent on the substitution pattern of the substrates. 

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