Norbornenes hydration

Formal hydration of the double bond appeared by the hydroboration-oxidation sequence. Desymmetrization reactions with catalytic asymmetric hydroboration are not restricted to norbornene or nonfunctionalized substrates and can be successfully applied to meso bicyclic hydrazines. In the case of 157, hydroxy derivative 158 is formed with only moderate enantioselectivity both using Rh or Ir precatalysts. Interestingly, a reversal of enantioselectivity is observed for the catalytic desymmetrization reaction by exchanging these two transition metals. Rh-catalyzed hydroboration involves a metal-H insertion, and a boryl migration is involved when using an Ir precatalyst (Equation 17) <2002JA12098, 2002JOC3522>. 

Hydrates of RUCI3, IrCl3, and OSCI3 are suitable catalysts for the ROMP of norbomene in aqueous and alcoholic solvents. Ruthenium trichloride hydrate is used for the industrial production of poly(norbornene). These hydrates act for the ROMP of norbomene and norbomene derivatives in pure water through an emulsion process (18). 

A study of acid-catalysed hydration of norbornenes and nortricyclanes gave a-values for the protonation which correlate well with those for the solvolyses of 2-norbomyl tosylates. This indicates that the first formed cations for both reactions are of a similar character44. 

Acid-catalysed hydration of 2-norbornen-5-one (27) in aqueous HCIO4 results in the formation of hydroxyketone 28 and lactone 29 as the major products. Kinetic measurements suggest complex rearrangement pathways60. 

Soon after the discovery of the alkene metathesis reaction, reports indicated that complexes of ruthenium, osmium, and iridium could initiate ROMP. Michelotti et al. initially reported the polymerization of norbornene and its derivatives catalyzed by the hydrates of RuC13, OsCl3, and IrCl3 in refluxing ethanol (Eq. 1) [22, 23],... 

It has been known for some time that norbornene undergoes ring-opening metathesis polymerization in the presence of Ziegler-Natta catalysts,reduced oxides of Cr, Mo, and and hydrated halides of Ru, Os, and Ir, resulting in an unsaturated polymer, poly(l,3-cyclopentylenevinylene). Norbornene also undergoes cationic polymerization in the presence of C2H5AlCl2, and FRP in the presence... 

Since reactivity of alkenes increases with increasing alkyl substitution, hydration is best applied in the synthesis of tertiary alcohols. Of the isomeric alkenes, cis compounds are usually more reactive than the corresponding trans isomers but strained cyclic isomeric olefins may exhibit opposite behavior. Thus, for example, raras-cyclooctene is hydrated 2500 times faster than cis-cyclooctene (98). Similar unusually high protonation rates were also measured for strained bridgehead alkenes. This may be attributed to the high groundstate strain (in the case of bicyclo[3.3.1]non-l-ene) or the formation of the nonclassical norbomyl cation when norbornene is protonated (95). 

Hydration Working at the hood, add 1.0 g of norbornene in small pieces to the stirred solution of aqueous sulfuric acid. Continue stirring the mixture until all of the norbornene dissolves. Cool the flask briefly m an ice-water bath if the mixture becomes noticeably warm, but do not cool the contents of the flask below room temperature. Stir this solution for 15-30 min. Prepare a solution of 1.5 g of potassium hydroxide in 7.5 mL of water. 

Exo-Norborneol (53) contains three centers of chirality, but the product obtained from the hydration of norbornene (52) in this experiment is optically inactive,... 

RuCls hydrate is known to be a metathesis initiator since many years [170-172] and it is used in combination with HCl in butanol for the polymerization of norbornene in industrial scale (see Section VII) [81]. Its advantage is the tolerance towards functional groups, however, the induction periods are long and only a small amount of the employed Ru becomes catalytically active [100,171]. 

Nortricyclyl and Quadricyclyl Systems.—The studies of the kinetics of acid-catalysed hydration of exo- and endo-norbornen-2-ols, referred to above, have been extended to include 3-nortricyclanol, 1-methyl-cis- and -rra s-3-nortricyclanols, and 3-methyl-3-nortricyclanol. Solvent deuterium-isotope effects are interpreted in favour of an A-S 2 hydration of the three-membered carbon ring of the secondary alcohols, or an A-1 mechanism for the tertiary alcohol in which case the rate-determining step is the formation of a carbocation (probably the 3-methyl-3-nortricyclyl cation) by elimination of water. 

H) Emulsion and miniemulsion polymerization Emulsion-type polymerizations for ROMP of norbornene and its derivatives were first reported using hydrates of Ru, Ir, and Os four decades ago. " However, polymerization rates were very low. ROMP using water-soluble ruthenium carbene complexes as catalysts was used to polymerize functionalized 7-oxanorbornenes not only in water and methanol, but also in aqueous emulsions. Gationic water-soluble aliphatic phosphines were used in the synthesis of the ruthenium carbene complexes. The polymer polydispersity was low (1.1-1.3), although few details of the dispersed phase polymerization were reported. 

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