Styrene norbornene

Reaction of 1,3-diones with propargylic alcohols leads to 3-acylfurans. Using other Lewis acids such as FeCU the reaction stops short of cyclization. Alkylation by alkenes (styrene, norbornene, cyclopentadiene, dihydropyran,. ..) affords moderate yields of the adducts.Again, InCU appears to show a special catalytic activity, as AICI3, TiCU, MnCl2, Bids are ineffective. 

Olefin epoxidation is not only important in the manufacture of bulk chemicals, e. g. ethylene and propylene oxides, but is also a widely used transformation in the fine-chemicals industry [1], Ethylene oxide is manufactured by vapor-phase oxidation of ethylene, with air or oxygen, over a supported silver catalyst [2], This method is not generally applicable as olefins containing allylic or other reactive C-H bonds give complex mixtures of products with low epoxide selectivity. The method has recently been extended to some other olefins that do not contain reactive allylic C-H bonds, e. g. butadiene, styrene, norbornene, and tert-butyl ethylene [3]. Some of these products, e. g. butadiene monoepoxide and styrene oxide, have potential applications as fine chemicals/intermediates. 

The introduction of metallocene and other single-site technologies (Fig. 31) made possible new process/ comonomer combinations, use of novel comonomers such as styrene, norbornene, and carbon monoxide, and seemingly impossible property combinations. Potential adaptation of polyolefin manufacturing technologies to the production of engineering thermoplastics is possible. 

Titanocene catalysts do not catalyze the hydrosilation of most internal olefins, although they can attach active olefins such as styrene, or norbornene to the growing polymer chain ends. The zirconocene-based catalysts, on the other hand, can be powerful hydrosilation catalysts and the remarkable copolymer synthesis shown in Equation 3 can be easily achieved under mild conditions (V7). 

The side products of the reaction between benzoylnitromethane 279 and dipolarophiles (norbornene, styrene, and phenylacetylene) in the presence of l,4-diazabicyclo[2.2.2]octane (DABCO) were identified as furazan derivatives (Scheme 72). The evidence reported indicates that benzoylnitromethane gives the dibenzoylfuroxan as a key intermediate, which is the dimerization product of the nitrile oxide. The furoxan then undergoes addition to the dipolarophile, hydrolysis, and ring rearrangement to the final products (furazans and benzoic acid) <2006EJ03016>. 

In a manner similar to that of the bis-silylation of internal alkynes shown above, the use of unsymmetrical disilanes with basic / //-phosphines is effective for intermolecular bis-silylation of terminal alkenes (Equations (32) and (33)).6 Although the regioselectivities need to be improved, clean bis-silylations of 1-octene, styrene, and norbornene have been achieved in high yields. 

Norbornene also undergoes silastannation from the exo-side under identical conditions (Equation (112)). However, ordinary alkenes such as 1-hexene, styrene, and cyclohexene fail to react with silylstannanes. 

Table 2 Hydroboration of norbornene, indene, and styrene using catecholborane...

Application of these ligands to the hydroboration-oxidation of styrene proceeded with moderate yields and much lower enantioselectivities than for norbornene. The best result was with (R, R)-38, which afforded (A)-l-phenyletha-nol in 61% yield and 42% ee. However, Bianchini s (R, 7 )-BDPBzP 39 was even less efficient for this substrate, and gave both poor yields (29%) and poor enantioselectivities (26% ee) for the hydroboration of styrene at 0°C.84... 

In this process, double bonds were found to be less reactive than triple bonds. Thus norbornene or styrene were hydrocarboxylated in low yields (10-40%) [121]. In unconjugated as well as conjugated ene-ynes, only the alkyne moiety was carboxylated with regio- and stereoselectivity similar to that observed for alkynes [122]. 

The kinetics of the reaction of [Ru (0)2(poi with various alkenes have been investigated either in CH2Cl2/MeOH or CH2Cl2/Hpz. In the absence of MeOH or Hpz, clean kinetics are not always observed, presumably because dimerization or disproportionation of the intermediate Ru =0 species occurs at comparable rates as epoxidation. The reactions have the following rate law rate = k[Ru (0)2(por)][alkenel. The rate constants for the oxidation of styrene are in the range 6 x 10 —4.8 x 10 s. The oxidation of norbornene occurs at... 

The first system is based on a poly (norbornene)-supported Co salen and the second system is based on a poly(styrene) backbone. For the poly (norbornene) system, a homopolymers and several different copolymers were prepared (44), with varying fractions of Co salen side-chains and spacer side-chains (Figure 3, copolymer la-c and homopolymer Id). For the poly (styrene) system, both homopolymers of salen-containing monomers and copolymers with styrene (45,46) were prepared (Figure 3, copolymer 2a-c and homopolymer 2d). 

Poly (norbornene)-supported Co(III)-Salen complexes (44) and poly (styrene)-supported Co(III)-Salen complexes (45,46) were synthesized via newly developed procedures. In particular, a new, high-yielding, one-pot synthesis of non-symmetrical salens was developed (46). Hydrolytic kinetic resolutions were carried out at room temperature and the products were characterized by chiral GC. 

At present, phosphoramidites represent the most promising ligand class for the hydrovinylation reaction, both for the excellent activities and enanioselectivities. The synthetic potential embraces not only styrene and styrene derivatives but also norbornene [54] and 1,3-dienes [55]. 

More recently, it was demonstrated that 80 is a catalyst for the partial oxidation of olefins using dioxygen (230). For example, dry propene was oxidized to acetone when water vapor was present in the catalyst stream, some propanal could also be detected. Other reactions reported included the conversion of styrene to acetophenone and phenylacetaldehyde in an 80 20 product ratio, and 2-norbornene to 2-norbomanone and cyclohexene-4-carboxyaldehyde in a 70 30 product ratio. 

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