Esters stannane

SYNS N,N-DIMETHYLDITHIOCARBAMIC ACID S-TRIBUTYLSTANNYL ESTER STANNANE, (piMETH-YLTHIOCARBAMOYL)THIO)TRIBUTYL-... 

SYNS CYANIC ACID, TRIMETHYLSTANNYL ESTER STANNANE, CYANATOTRIMETHYL-... 

SYNS ACETIC ACID, CYANO-, TRIPHENYLSTANNYL ESTER STANNANE, (CYANOACETOXY)TRIPHENYL-... 

The preparations of the various types of organometallic compounds that can be used as cross-coupling parmers are described earlier in this chapter. Most magnesium and zinc compounds have to be prepared, then used, as needed. However, boronates (i.e. boronic acids and esters), stannanes and silanes are much more stable to air and water, and many of them can be stored for long periods. 

Acetic acid, ((butylstannylidyne)trithio)tri-, triisooctyl ester Acetic acid, 2,2, 2"-((bu lstannylidyne)-tris(thio))tris-, triisooctyl ester Butyltin tris(isoootyl mercaptoacetate) Butyltris(2-ethylhexyloxycarbony-methylthio)stannane CCRIS 4692 EINECS 247-295-4 Stannane, butyltris((carboxymethyi)thio)-, triisooctyl ester Stannane, butyltris(carboisooctoxymethylthlo)- Stannane, butyltrls(isooctyloxycarbonylmethylthio)- Stannane, n-... 

Stannane methyltris ((carboxymethyl) thio) tris isooctyl ester Stannane, tris (((isooctylthio) acetyl) oxy) methyl-. See Methyltin tris (isooctylthioglycollate)... 

The alkaloid dubamine contains a single bond between the two heteroarene units. This lond was formed in 79% yield by the generally valuable palladium-catalyzed eoupling of an ryltrimethylstannane with an aryl triflate (see section 1.6). The requisite stannane was pre-ared from l,3-benzodioxol-5-yl triflate and hexamethyldistannane with the same palladium atalyst, the triflate ester was obtained from 2(1 f/)-quinolinone and trifluoromethanesulfonic jihydride (A.M. Echavarren, 1987). An earlier attempt to perform this aryl coupling by dassical means gave a yield of only 1 %. 

Selenium oxide (SeO,) [7446-08-4], 25 Silane, tnchloro [ 10025-78-2], 83 Sodium azide [26628-22-8], 109 Sodium hydride [7646-69-7], 20 Stannane, tetrachloro- [7646-78-8], 97 Sulfuric acid, diethyl ester [64-67-5], 48 dimethyl ester [77-78-1], 62 Sulfuryl chloride isocyanate [1189-71-5], 41... 

Scheme 10.17 illustrates allylation by reaction of radical intermediates with allyl stannanes. The first entry uses a carbohydrate-derived xanthate as the radical source. The addition in this case is highly stereoselective because the shape of the bicyclic ring system provides a steric bias. In Entry 2, a primary phenylthiocar-bonate ester is used as the radical source. In Entry 3, the allyl group is introduced at a rather congested carbon. The reaction is completely stereoselective, presumably because of steric features of the tricyclic system. In Entry 4, a primary selenide serves as the radical source. Entry 5 involves a tandem alkylation-allylation with triethylboron generating the ethyl radical that initiates the reaction. This reaction was done in the presence of a Lewis acid, but lanthanide salts also give good results. 

It was further shown that the nonracemic stannane 70 can be prepared from the Mosher ester derivative 69 through reductive cleavage and BOM protection (equation 28). Lithiation and methylation gave the nonracemic ether with retention of configuration59. 

Tris (dibuty Ibis (2-hydroxy ethylthio)stannane) O-ester with bis(boric acid) XK 4860000... 

The trialkylstannyl intermediates required in this synthetic sceme to prepare labelled compounds can be obtained in several ways. One method is the addition of the organotin hydride to the carbon-carbon triple bond of an alkyne (equation 93). These reactions have already been discussed in detail above. A second approach is to add a trialkylstan-nylvinyllithium to a ketone (equation 95), and a third method involves adding trialkylstan-nyllithium to a /J-halo, a, /J-unsaturated ester (equation 96). Although this last reaction gives a suitable trialkylstannane, these stannanes have proven to be inert in the destanny-lation reaction and, therefore, have not been used extensively to prepare radiolabelled compounds. 

The alkoxyalkynylstannanes show the familiar instability associated with alkoxyalkynes. The decomposition of a trialkyl(ethoxyalkynyl)stannane, 17, can be rationalized as follows. Elimination of ethene and rearrangement gives the stannylketene, which reacts with the alkoxyalkyne to give the ester 18 and the distannylketene 19 as the observed products (Equation (87)).241,250... 

A novel aromatic substitution reaction with electron-deficient radicals, which avoids the use of stannanes, is promoted by the addition of tetra-n-butylammonium bromide [54]. Iodoacetonitrile and iodoacetic esters react with pyrroles and indoles in good to high yield upon photolysis in the presence of 2-methyloxirane and sodium thiosulphate (Scheme 6.34). 

AT-Boc group, was followed by reductive debenzylation of 30 and Yamaguchi lactonization of the resultant hydroxy acid to provide macrodiolide 31 in 25% yield accompanied by a dimer. Finally, removal of the N-Boc group and reductive N-methylation yielded pamamycin-607 (lb). In total, ca. 40 steps were required to access the target from ester 4, aldehyde 22, and allyl stannanes 10 and ent-lO. 

Alternatively, 138 can be converted to CBZ carbamate 142 using standard conditions (Scheme 4.30). This 5-bromoisoindoline was transformed to stannane 143 in one step with bistributyltin in the presence of a palladium catalyst. The stannane was treated with 136 under Stille conditions to afford coupled product 144. The resulting ester was hydrolyzed with sodium hydroxide, and the CBZ group was removed under hydrogenolysis conditions to deliver garenoxacin (4) (Hayashi et al., 2002). 

Preparation of some azulenylmagnesium species was achieved by the halogen-magnesium exchange reactions of iodoazulenes with lithium tributylmagnesate at low temperatures (equations 29-33) . The reactions offer access to a variety of functionalized azulenes including azulenylphosphine, -stannane and -boronic ester. 

The cyclopropanation of alkenes using zinc carbenoids displays excellent chemoselec-tivities. A large number of functional groups are compatible with these reagents, such as alkynes, silanes, stannanes, germanes, alcohols, ethers, sulfonate esters, aldehydes. 

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