Stannyl phosphines

The same stannyl phosphine will also add to both terminal and non-terminal alkynes32, giving stannyl-substituted alkenes. In the case of terminal alkynes E- and Z-isomers are formed, with a mixture of the two possible regioisomers. Total yields are 60-80%, with 60-90% preference for the E-isomer, depending on the substituents on the alkyne, although exact experimental details are not given (reaction 24). 

Acidolysis of an aminostannane with a phosphine or arsine provides a clean route to the stannyl-phosphines and -arsines (Section 16.1.3.1), and, under more forcing conditions, the phosphines can be prepared from bis(tributyltin) oxide.73... 

If the cyclic trimer (9.316) is heated, pentameric phenylphosphine is obtained (9.326). Like their silicon and germanium analogues, stannyl phosphines are easily hydrolysed (9.327), or oxidised to phosphinates (9.328). The P-Sn bond is broken by alkyl halides as in Equation 9.329. 

Stannyl phosphines form metal complexes, for example, (Me3Sn)3P Ni(CO)3. With tin halides, trimethylphosphine forms low-temperatnre complexes 80X4 PMcj and SnX4 2PMe3 in which the Sn atoms have trigonal bipyramidal and octahedral confignrations, respectively, with trans PMej gronps (9.330). A stable phosphonium componnd is produced in reaction (9.331) [9]. 

Compounds with Sn-O-P linkages are obtainable from distannoxanes (9.334) as well as by oxidation of stannyl phosphines (9.328). 

Tinney and StUle reported the first C—P bond formation using silyl and stannyl phosphines with aryl iodides (Scheme 20.69) [231], Under these conditions, aryl chlorides and aryl bromides are ineffective. The coupling of terf-butyl(trimethylsilyl)phosphine has been subsequently accomplished with aiyl halides [232], Rossi and coworkers reported the coupling of (trialkylstan-nyl)diphenylphosphines with aryl iodides [233]. The reaction conditions can be extended for the coupling of aryl triflates using Cul as cocatalyst [234]. 

SCHEME 20.69 Phosphination of aiyl iodides with sdyl/stannyl phosphines. 

T rimethylsilylethoxy-mcthyl)-2-(tri-n-butyl-stannyl)indole 3-Bromopropene, Pd,(dba)j, tri-(2-furyl)phosphine 93 [1]... 

A bis(stannyl)bis(phosphine)palladium complex has a twisted square planar structure and shows facile unimolecular twist-rotation.170... 

OR, -SEt, and -NR2 migration from a tertiary phosphine to phosphenium P (from 32 to 31 in Scheme l).33 Another one is 1,3-alkyl migration from a stannyl ligand to phosphenium P (from 36 to 39 in Scheme 2).23,24 34,36 48 In this reaction, a phosphenium complex is converted into a stannylene complex. This reaction corresponds to migration of a double bond from M=P to M=Sn. The last one is 1,3-alkoxy migration from a phosphite... 

A number of stannyl-zinc and -cadmium compounds have been prepared by reaction of a tin-alkali metal compound with a zinc or cadmium halide, or a tin hydride with an alkyl-zinc or -cadmium compound. The coordination of a ligand such as a triphenyl-phosphine, TMEDA, or bipyridyl, or a solvating solvent such as DME, both enhances the nucleophilicity of the alkyl group in the alkylmetallic compounds and stabilises the stannylmetallic product. Thus triphenyltin hydride reacts with diethylzinc or diethylcad-mium in pentane or benzene with separation of metallic zinc or cadmium, but with a preformed complex, or in a coordinating solvent, the distannylmetallic compound is formed (e.g. equation 19-32). 

Addition of carbon monoxide to the tris( 74-naphthalene)zirconate(2—), 5, in the presence of stannyl chloride affords the heptacoordinate complex [Zr(CO)5(SnMe3)2]2 12 (Scheme 4).8 The related bis(phosphine) zirconate anion, [Zr(CO)4(dppe)SnMe3] 13, has been prepared by treatment of 7 with Me3SnCl at low temperature followed... 

The stannylated product 272 can be induced to undergo ring-opening by treatment with MeLi, either via a transmetallation or the ate complex. This overall sequence provides the reductive ring opened product 273 with complementary regioselectivity to that obtained through nickel and phosphine-catalyzed hydro-alumination. 

Addition and cycloaddition. In the (dba)3Pd2-catalyzed hydrostannylation of alkynes the legiochemistry is controlled by the phosphine ligands. ( )-l-Tributylstannylalkenes are produced preponderantly in the presence of CysP or t-Bu3P, but much more 2-stannyl-l-aUcenes are obtained with PhsP. ... 

Stannylphosphines react like tertiary phosphines with carbon disulfide, a P-C bond being formed the zwitterionic adducts, however, cannot be isolated and stabilize themselves by migration of the stannyl group to sulfur 138... 

The reaction of bis(pentafluoroethyl)phosphinic chloride with two equivalents of BuaSnH leads to stannyl derivative (C2F5)2POSnBu3, that gives the corresponding phosphinous acid. Theoretical calculations suggested that the secondary phosphine oxide is only a minor component in the tautomeric equilibrium (Scheme 6). ... 

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