Norbornene-2-carboxylic acid

Corey and coworkers suggested that cyclic cationic intermediates are involved in the formation of 3-methoxynorticyclene (68) from either endo- or exo-5-norbornene-2-carboxylic acid (67), and for the formation of gxo-2-methoxynorbornane (70) as the only volatile product from the electrolysis in MeOH (at Pt anode) of either exo- or endo-norbornane-2-carboxylic acid (69). These results are consistent with the suggested formation of the same bridged ions in the solvolysis reaction . ... 

Based on the 13C-NMR shifts, one can surmise that the electronic effect of the substituent on the C = C bond is minimal. Thus, the vinyl carbons of the norbornene resonate at 135.5 ppm, while those of 5-norbornene-2-carboxylic acid ethyl ester appear at 137.7 and 132.5 ppm (endo) and 138.1 and 135.9 ppm (exo). 

Norbornene-2-carboxylic acid (8) was obtained in acceptable ee by the use of a chiral auxiliary. Optically active tetrahydropyrimidones 6 underwent Diels-Alder cycloadditions with cyclopentadiene (5) in water at room temperature. Subsequent removal of the auxiliary was achieved by boiling the carboxamide 7 in water (Scheme 5.2). The cycloaddition conversions were at least 90% and the endo adduct was the prevalent diastereoisomer. Using 70% aqueous ethanol as reaction medium, both the endo/exo ratio and ee were lower than in pure water. Since tetrahydropyrimidones 6 can be prepared in water from L-asparagine and a suitable aldehyde and subsequent acylation with acryloyl chloride, the entire synthesis of 8 was performed in water by one-pot procedure. The yield was fair, but the ee of norbornene carboxylic acid 8 was lower than that obtained by using a step-by-step procedure. This result was probably due to some acryloyl chloride being hydrolyzed to acrylic acid, which then reacted with 5 in a non-stereo-biased manner. 

Scheme 40 Anodic decarboxylation of a norbornene carboxylic acid.

For example, a homopolymer of norbornene carboxylic acid butyl ester can be prepared by addition polymerization using tricyclohex-ylphosphine and palladium(II) acetylacetonate as a catalyst (9). 

Infrared spectroscopy provides a convenient method for studying the deprotection kinetics of resist polymers. For example, the deprotection kinetics of some alicyclic polymer resist systems comprising (i) poly(methylpropyl bicyclo[2.2.1]-hept-5-ene-2-carboxylate-co-bicyclo[2.2.1]hept-5-ene-2-carboxylic acid) (trivial name poly(carbo-t-butoxynorbomene-co-norbornene carboxylic acid) [poly(CBN-co-NBCA)] (I) and (ii) poly(methylpropyl bicyclo[2.2.1]hept-5-ene-2-carboxylate-co-maleic anhydride) (trivial name poly(carbo-t-butoxynorbomene-co-maleic anhydride) [poly(CBN-aZr-MAH)] (11) and containing triphenylsulfonium... 

Diels-Alder addition of tetrachlorocyclopentadiene dimethylketal to endo-5-norbornene carboxylic acid produces (459). Ketal cleavage (H2SO4), cheletropic loss of CO (reflux in o-dichloro benzene), and aromatization (bromine in hot chlorobenzene) affords the endo-acid (460 X = Cl) which can be dechlorinated by reaction with Ni-Al alloy and alkali to give (460 X = H). The clean retention of stereochemistry in reaction sequence is suggested to be of value in the general synthesis of alicyclic-substituted benzonorbornenes the methyl ester of (460 X = H) can likewise be prepared without epimerization. ... 

Nonadienoic acid, 4-methyl-, trans, ethyl ester, 53, 116 Nonan-5-ol, 52, 22 D-NORANDROST-5-EN-36-0L-16-CARBOXYLIC ACIDS, 52, 53 Norbornene, with ethyl tri-... 

The living character of the ring opening metathesis polymerization described earlier in this review enables a simple preparation of functionalized norbornene-based monoliths. Adding one more in situ derivatization step that involves functional norborn-2-ene and 7-oxanorborn-2-ene monomers that react with the surface-bound initiator, the pores were provided with a number of typical functional groups such as carboxylic acid, tertiary amine, and cyclodextrin [58,59]. 

An exception is norbornene, which after 84% conversion in the presence of PtCl2/SnCl2/(—)-BPPM gives exclusively < .TO-2-formylbicyclo[2.2.1]heptane with 98.7% aldehyde selectivity and 60 % ee12. The product can be converted to the corresponding carboxylic acid upon oxidation without loss of enantiomeric purity. If the hydroformylation reaction is carried out in triethyl orthoformate as solvent, the aldehyde is trapped as the acetal. Thus, higher temperatures with higher conversions and yields can be applied without racemization of the product. 

Polynorbornene bearing a pendant tert-butyl ester was imaged in a negative mode using an onium salt PAG [241]. This highly hydrophobic polymer failed to develop in a positive tone in aqueous base (see the tBOC resist). Norbornene bearing carboxylic acid (NBCA) was copolymerized with NBTBE as a polar group [271]. Unlike the phenolic 248 nm system,however, the dissolution rate of the NBCA copolymers in aqueous base is not a smooth function of the copolymer composition and the concentration of the acidic unit cannot exceed ca. 20 mol%. Typically, the NBCA copolymer does not dissolve in aqueous base when the NBCA concentration is below 20 mol% and dissolves extremely rapidly (>10,000 A/s in 0.26 N TMAH) when the acid concentration is above... 

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