Dibutyltin oxide, and

Anodic oxidation of a mixture of ds-cyclohexane-l,2-diol and cyclohexanol in methanol containing dibutyltin oxide and Et4NBr provides 2-hydroxycyclohexanone selectively, while cyclohexanol is recovered almost completely (Fig. 28) [146]. The cyclic intermediate dibutyl-(l,2-dioxycyclo-hexyl) stannan is oxidized indirectly by Br+. 

Three cyclic initiators from dibutyltin oxide and 1,2-ethanediol, 2-mer-captoethanol, and 1,2-dimercaptoethane as indicated in Fig. 43 were prepared. Polymerizations of L-lactide and racemic D,L-lactide were conducted... 

In general reaction of an alcohol with the appropriate anhydride or acid chloride in pyridine at 0-20 JC is sufficient. In the case of tertiary alcohols, acylation is very slow in which case a catalytic amount of 4-dimethylaminopyridine (DMAP) can be added to speed up the reaction by a factor of 10,000. Reaction of polyols with acyl chlorides (1.2 equiv) in the presence of hindered bases (2.0equiv) such as 2,4,6-collidine, diisopropylethylamine or 1,2,2,6,6-penta-methylpiperidine in dichloromethane at -78 °C leads to selective acylation of a primary alcohol. Primary alcohols can also be acylated selectively with isopro-penyl acetate or acetic anhydride in the presence of a catalytic amount of 1,3-dichlorotetrabutyldistannoxane 325.1 [Scheme 4.325].602 The catalyst 325.1 is available commercially or can be easily prepared by simply mixing dibutyltin oxide and dibutyldichlorostannane. No aqueous workup is necessary since the catalyst can be removed by simple chromatography. 

The most important hydrogen bond donating group in directed epoxidations is the hydroxy group. For allylic or homoallylic alcohols, peracids or tert-butyl hydroperoxide/vanadylbis[2,4-pentanedionate] (see Houben-Weyl, Vol. IV/la, p 231) are generally the most efficient reagent systems less common catalysts are tri-te/ f-butoxyaluminum, dibutyltin oxide, and molybdenum- and titanium-based systems (see Houben-Weyl, Vol. IV/la, p 227, Vol. E13/2, p 1176). The two classes of reactions show distinct differences in their stereoselectivity patterns. 

The tin-mediated strategy was applied to my o- and chiro-inositol. Thus, treatment of myo-inositol with 5 equiv of dibutyltin oxide and allyl bromide in the presence of tetrabutylammonium bromide furnished two major tetraallylated products 119 and 120. Parallel results were obtained when crotyl bromide was used. When 3 equiv of the tin oxide were used, 1,3,4-triallyl ether 121 was a major product (Scheme 3-18).57 Five membered cyclic stannylene derivatives like 123 may be formed predominantly at the 1,2-cis-diol site and then the more reactive alkoxide reacts with an electrophile, as is shown in Scheme 3-18.58... 

The reaction between dibutyltin oxide and bis-thiols leads to cyclic products including the six-membered ring product 27 (Scheme 8) <2000PSA3656>. Reaction of 27 with bis-acid chlorides affords the polymers 28. 

It is also possible to regioselectively mono-O-tosylate various nonprotected hydroxyl functionalities, as illustrated in Scheme 1. This method employs a preliminary activation of a glycopy-ranoside with Dibutyltin Oxide and usually requires the use of a basic catalyst such as 4-Dimethylaminopyridine (DMAP) in conjunction with tosyl chloride. Regioselectivity differs markedly from acylation reactions and is thought to be a function of changes... 

Methyl p-D-galactopyranoside, activated with dibutyltin oxide and treated with tetra-O-pivaloyl-a-D-glucopyranosyl bromide, gave the 6-p-linked product in 72% yield. In this work the term open glycosylation is used to imply an unprotected acceptor strategy. Related work with the glucuronic acid analogue as donor is reported in Section 1.4.8. 

It has been supposed [8] that the formation of tetralactones such as LI 586 proceeds through electrophilic attack of the anhydride carbonyl at stannoxane oxygen, followed by extrusion of dibutyltin oxide and liberation of the macrocyclic ligand product. 

The preparations of racemic 1,3,4,6-tetra-O-allyl and 1,3,4,5-tetra-O-allyl myoinositol from myo-inositol, excess dibutyltin oxide and allyl bromide have been reported. The latter compound was resolved via its (-)camphanate ester. The 1,3.4-tri-O-allyl nQ o-inositol was also made by using three equivalents of dibutyltin oxide. 

A new reagent to effect the amide-to-nitrile dehydration is trimethylsilyl polyphosphate, and new reagents for the desulphydration of thioamides are dibutyltin oxide and formamide chlorides. A-(Phenylsulphonyl)-benzo-hydrazonyl azide decomposes in the presence of triethylamine to give benzo-nitrile. ... 

A similar product can be formed through reaction between dibutyltin oxide and butanol by heating in toluene at 110°C and then heating the resulting dioxide to about 200°C imder reduced pressure. However, in tetrahydronaphthalene (boiling point 207°C) phenols give the dialkyltin diphenoxides directly. ... 

Treatment of thymine ribonucleoside with dibutyltin oxide and R4NCI in the ptesoice of tosyl chloride gives selectively the 2 -0-tosyl derivative, whereas the presence of a substituent at C-T gives mostly the 3 -0-tosyl regioisomers 152 (R=Me, CN). 2, 3 -0-Thi(Miocarb(Hiates were also prepared directly from the unprotected nucleosides uting stannylene activation.234 O... 

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