Tin-acetylene

The acetylene unit is also introduced by the reaction with silyl or tin acetylene in the presence of a Lewis acid. Tin acetylene was used in order to introduce acetylene into glucose, galactose, and mannose (O Table 5) [32], while C-glycosylation of deoxyhexopyranose was carried out with silylacetylene (O Table 6) [33]. These examples indicate an easy and reliable route for the preparation of a-glycosylacetylene (a-sugar acetylene). 

The overwhelming majoritiy of currently known alkynyliodonium species are prepared by interaction of a terminal, sila- or tin-acetylene with an electrophilic X -iodane, also referred to as a 10-1-3 hypervalent species [14]. Key reagents are iodosobenzene (4), [hydroxyftosyl-oxy)iodo]benzene (5, HTIB) [15] the -oxo-X -iodane 6 [16], and cyano(phenyl)iodonium triflate 7 [17]. 

A more general, simpler procedure [20] takes advantage of the in situ formation of the p-oxo-bis-triflate (6 R=CF3) and its interaction with a sila- or tin-acetylene [Eq. (2)]. This methodology affords a wide variety of stable, alkynyl(phenyl)iodonium triflates 10 in good to excellent yields and is applicable to the synthesis of the parent [21] ethynyl(phenyl)iodonium triflate (10 R=H) from n-Bu3SnC=CH. 

A number of interesting bis-iodonium acetylenes and bis-iodonium diynes were reported in the early 1990s. Reaction of bis-tin-acetylene 29 and bis-tin-diyne 31 with two equivalents of 7 in cold dichloromethane results in the formation of novel bis-iodonium ethyne 30 [24] and bis-iodonium diyne 32 [39], respectively [Eqs. (15), (16)]. 

Ph3SnCl and propargylmagnesium bromide give a 90 10 mixture of the acetylenic and allenic tin derivatives, while in the case of Me3SnCl this ratio is 30 70 . 

Aryl-S02Cl. At present only a few data concerning electrophilic 1,3-substitution with allenic and acetylenic tin or silicon compounds are available. 

Fabiano, B., Pastormo, R., and Solisio, C. 1999. Explosion at an Acetylene Plant A Methodological Approach to Accident Analysis. IChemE Loss Prevention Bnlle-tin. Issue 145 (February 1999). 

Certain 1,5 diazabicyclo[3 3 0]oct-2-enes can be transformed unexpectedly into 4//-5,5-dihydro-l, 2 diazepines on heating [209] 1,5-Dipoles formed on heating of l,5-diazabicyclo[3 3 0]oct-2-enes [210] can be trapped with olefins to give [3+2] cycloadducts At elevated temperatures, they undergo a [3+2] cycloreversion Tins reaction sequence offers a simple route to dienes with interesting substitution patterns, for example, 1,1 bis(trifluoromethyl)-l,3-butadiene [211] The [3+2] cycloadducts that arise from the reaction of the 1,5 dipoles with acetylenes undergo... 

Nicodemus obtained mixtures of ethylamines on passing mixtures of NH3 and acetylene at 280-290°C over zinc chloride on pumice [232, 233] or at 350°C over a mixture of zinc nitrate, tin chloride, siUca and charcoal on diatomaceous earth (Eq. 4.56) [234]. 

The two acetylenic functions in the silicon or tin derivative make possible a competition between 1 1 and 2 1 reactions (Scheme 39, pathway b), and the product ratio depends significantly on the reaction conditions. For silicon derivatives an excess of 1-boraadamantane in the reaction mixture (acetylenic component added to 1-boraadamantane) leads to the octacyclic compounds 88 (up to 60%), while when the much more reactive 1-alkynyltin analogues are used, a second intramolecular 1,1-organoboration often takes place <2001CEJ775>. The stmcture of 88c (M = Sn, R = Me, R1 = SiMe3) was confirmed by X-ray analysis <2001CEJ775>. 

Other tin reagents have found use in Pd-catalyzed cross-couplings with halopyridines as well. The Stille coupling of 3-iodopyridine with ethoxy(tributylstannyl)acetylene gave rise to 3-ethoxyethynylpyridine (100), which was then hydrolyzed to the corresponding ethyl 3-pyridylacetate (101) [88], Carbamoylstannane 102 was prepared by sequential treatment of lithiated piperidine with carbon monoxide and trimethyltin chloride. Stille coupling of carbamoylstannane 102 and 3-bromopyridine provided a unique entry to amide 103 [89],... 

The /3-trimethyltin-substituted alkenylborane 36 was prepared in situ by treatment of triethylborane with 1-lithio-l-hexyne to form the lithium 1-alkynyltriethyl-borate 35 followed by trimethyltin chloride (Scheme 20.9) [37]. The trimethyltin chloride-induced migration of an ethyl group from boron to the adjacent acetylenic carbon is stereoselective with the boron and the tin substituents in 36 cis to each... 

Transmetallations of vinylic tellurides deserve particular attention. These tellurides (prepared by anti-addition of tellurols to acetylenes, see Section 3.16.1.2) exhibit the Z configuration and therefore generate (Z)-vinyUithiums. These results are in sharp contrast to the earlier tin-lithium exchange performed with vinylstannanes (characterized by the E configuration), giving (ii)-vinyllithiums. ... 

Much of the interest in the polysilanes, polygermanes, and polystannanes involves their sigma delocalization and their sigma-pi delocalization when coupled with arenes or acetylenes. This is not unexpected since silicon exists as a covalent network similar to diamond. In exhibiting electrical conductivity, germanium and tin show more typical metallic bonding. Some polystannanes have been referred to as molecular metals. ... 

Magnesium nitrate, Tin(ll) fluoride, 4693 Manganese(lV) oxide, Calcium hydride, 4705 Molybdenum(VI) oxide, Graphite, 4717 Nitric acid, Formaldehyde, 4436 Nitric acid, Formic acid, 4436 Nitric acid, Formic acid. Urea, 4436 Nitric acid, Metal thiocyanate, 4436 Oxalic acid, Urea, 0725 Ozone, Acetylene, 4846... 

Tin can be measured readily at trace concentrations in aqueous solutions by flame or furnace atomic absorption spectrophotometry. For flame AA measurement, air-acetylene flame is suitable. The metal can be identified accurately at 224.6 nm. Tin also can be measured by other instrumental techniques such as ICP-AES, ICP/MS and neutron activation analysis. 

Metal-Oxygen Compounds. Clear examples of the addition of transition metal alkoxides to acetylenes are not known however, the addition of trialkyltin alkoxides has been reported. Triethyltin methoxide, for example, reacts with dimethyl acetylenedicarboxylate to give the vinyl tin derivative XVI (63). 

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