Distannoxanes

Cyhexatin [13121 -70-5], tricyclohexylhydroxystannane (147) (mp 195°C), rat oral 540 mg/kg, and fenbutatin oxide [13356-08-6], hexakis-(2-methyl-2-phenylpropyl)distannoxane (148) (mp 138°C), rat oral LD q 2630 mg/kg, are two novel tin acaricides used on deciduous fmits. They are inhibitors of oxidative phosphorylation. 

Shanzer and Mayer-Shochet have utilized disubstituted stannoxanes as covalent templates for the formation of tetralactones. In this procedure, a dialkyl stannoxane is condensed with a glycol to form a cyclic-distannoxane as illustrated below. In a typical preparation, the distannoxane (i) was dissolved in CCI4 (ca. 0.04 At) at reflux and sebacoyl chloride (2 eq) was added dropwise at reflux. After heating for 20 h, the solution was concentrated to a solid. Chromatography afforded the tetralactone in 30% yield. ... 

Distannoxanes, MeOH or EtOH in CHCI3, CH2CI2, PhH or THF. 1-0) Diacetates are selectively cleaved, but the selectivity goes down as the chain length increases. ... 

Disiloxane, tetramesityl-, 3,206 Disproportionation iridium catalysts, 4,1159 Dissolution nuclear fuels, 6, 927 Distannene, 3,217 Distannoxane, 1,3-dichloro-, 3,207 Distibine, tetraphenyl-, 2,1008 Distibines, 2,1008 Disulfido ligands metal complexes, 2,531-540, 553 bonding, 2, 539 electron transfer, 2, 537 intramolecular redox reactions, 2,537 reactions, 2, 537... 

The solid-state structure of tetrabutylbis(2,3 4,6-diisopropylidene-2-keto-L-gulonato)distannoxane has been determined. The [Bu2Sn(IV)] complex of D-lactobionic acid also proved to be oligomeric, containing octa- (within the chain) and pentacoordinated (at the end of the chain) Sn centers in a ratio of 2 4. ... 

According to Barbieri et al., it can not be excluded that some of the coordination sites are occupied by (Nj atoms of the nucleic acid constituents. The precipitate obtained from [Ph2Sn(IV)] would contain both the [R2Sn(IV)] -DNA complex and distannoxane [(Ph2SnCl)20]. The main products of the... 

The products are yellow or red solids when R = Me, Et, Pr, or Bu, they decompose below —10°, but when R = Ph, or, particularly, when R = Me iCH, the products are more stable. They are oxidized immediately in air to the corresponding distannoxanes, readily exchange the trialkyltin group with trialkyltin hydrides, and add across polar-substituted alkynes or azo compounds. 

When (62) was treated with ethyl vinyl ether the cycloadduct (63) is afforded. If (62) is reacted with electron donating dienophiles such as allyl alcohols, transesterification and intramolecular cycloaddition occurs in the presence of a catalytic amount of distannoxane catalyst to give cis-fused polycyclic systems such as (64) <96T733>. 

Whereas several reports of doubly bonded tin compounds being sensitive to decomposition in air are to be found in the literature, there is only one instance of a controlled oxidation. Tetrakis[bis(trimethylsilyl)methyl]-distannene was treated with Me3NO to give the corresponding cyclo-1,3-distannoxane."2... 

An unusual class of heterocydes are polyketide-derived macrodiolide natural produds. The groups of Porco and Panek have recently shown that stereochemically well-defined macrodiolides of this type can be obtained by cyclodimerization (transesterification) of non-racemic chiral hydroxy esters (Scheme 6.154) [301]. Preliminary experiments involving microwave irradiation demonstrated that exposing dilute solutions of the hydroxy ester (0.02 m) in chlorobenzene to sealed-vessel microwave irradiation conditions (200 °C, 7 min) in the presence of 10 mol% of a distannoxane transesterification catalyst led to a 60% isolated yield of the 16-mem-bered macrodiolide heterocycle. Conventional reflux conditions in the same solvent (0.01 m in the hydroxy ester) provided a 75% yield after 48 h at ca. 135 °C. 

The difunctional distannoxanes XR2SnOSnR2X can also be prepared from the reaction of (R2SnO) with R2SnX2, or from (R2SnO) and the appropriate amount of the acid HX. A further alternative is to heat the dialkyltin oxide with saturated aqueous NH4X (X = F, Cl, Br, I, OAc) in refluxing dioxane, and this probably provides the best route to the fluorides FR2SnOSnR2F.331... 

Unless the organic groups are very large, the difunctional distannoxanes are dimeric in the solid state, with all the tin atoms rendered at least five coordinate. The two most common structural motifs are represented by the dichloride 37, where there are two four-membered rings about the central distannoxane core, and the dicarboxylate 38, where there are four six-membered rings about the center, but a number of variants on these basic models have been identified.347... 

If bridged bis(dichlorodistannoxanes), X2RSn SnRX2, are converted into the distannoxanes (usually by reaction with Buc2SnO), the products have a more complex structure, with the alternatives shown in Equation (134). 

Otera has reported that fluorous distannoxanes such as 23, which dissociate to give Lewis acidic species, catalyze transesterifications in or-ganic/fluorous solvent mixtures [8,9]. Although 23 was insoluble in toluene at room temperature, it dissolved at reflux and efficiently promoted the transformation in reaction D of Scheme 4, as well as others. The catalyst precipitated upon cooling, but a fluorous solvent extraction was utilized for recovery (100%). Another thermomorphic fluorous Lewis acid catalyst was developed by Mikami [11]. He found that the ytterbium tris(sulfonamide) 24 could be used for Friedel-Crafts acylations imder homogeneous conditions in CICH2CH2CI at 80 °C, and precipitated upon cooHng to -20 °C (reaction E, Scheme 4). 

Monomers 1 and 2 were also used as comonomers with dimethyl dialkanoates and monomers containing furan rings, for the synthesis of copolyesters by bulk polycondensations, in the presence of titanium isopropoxide or tetra-butyl-1,3-dichloro-distannoxane. In general, the biodegradability of the copolyesters of 1 decreased with increasing difuran dicarboxylate content, and copolymers... 

As an extension of the auto-association in organotin compounds, the 119Sn chemical shifts of a series of functionally disubstituted symmetrical distannoxanes, X.R2SnOSnR2.X, containing a range of X substituents have been measured (5, 6, 37, 73) and some results are shown in Table IX. 

---