5-Norbomene-2-carboxylic acid synthesis

A second method for the synthesis of organometallic polynorbomenes containing a bound azo dye involved the reaction of T -chlorotoluene- n -cyclopentadienyliion complex 21 with bifunctional azo dyes to yield the azo dye-containing organoiron compounds, which wctc then further reacted with 5-norbomene-2-carboxylic acid (16) to form the azo dye functionalized norbomene monomers, 24, shown in Scheme 7.7. 

Catellani [61] reported a palladium/norbomene-catalyzed synthesis of heteroatom-containing o-teraryls from aryl iodides and heteroarenes (including indoles and pyrroles) through double C-H arylation. Fagnou s group [62] applied their own protocol (Pd(II)/Ag(I)/carboxylic acid) to achieve the direct arylation of azaindoles. Itami [63] demonstrated the first iridium-catalyzed C-H arylation of heteroarenes (involving indoles and pyrroles) with aryl halides. 

Bazan reported on the synthesis of pseudo-tetrablock copolymers comprised of ethene and 5-norbomen-2-yl acetate, using the initiator system (LiPr2)Ni(q -CH2Ph) (PMes) [(LiPr2) = 77-(2,6-diisopropylphenyl)-2-(2,6-diisopropylphenylimino) propanamide] and 2.5 equivalents of Ni(cod)2 [bis(l,5-cyclooctadiene)nickel [121, 130, 131]. Square-planar nickel complexes with anionic P,0-chelate ligands were used by Goodall and coworkers for the co- and terpolymerization of norbomene and 5-norbomene-2-carboxylic acid ethyl ester with ethene [126]. 

A short synthesis of the carbocyclic analogue of S-phosphoribosyl-1-pyrophosphate from the known (C.R. Johnson et al.. Tetrahedron, 1984, 40, 1225) chiral ketone 72 has been described. Syntheses of carba-a-D-arabinofuranose and of the carba-nucleosides (+)-cyclaradine and (+)- caH>a>P-D-arabinofuranosyluraciI from key intermediate nitro-compound 73 have been reported. A short synthesis of Ohno s lactone, 74 in 54% overall yield from (+)-(lR)-e/u/o-5-norbomene-2-carboxylic acid, as a useful carbocyclic nucleoside precursor, has been reported." See Chapter 20 for the synthesis of carbocyclic tiazofurin and other carbocyclic nucleosides. 

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