- Process for preparing a compound containing a heteroaromatic group with one or more ether substituents
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A process for preparing a heteroaromatic compound having a heteroaromatic nucleus substituted with one or more ether groups comprising the step of: condensing at least one hydroxy-group of a compound having said heteroaromatic nucleus, said at least one hydroxy group (—OH) being substituted at α- or β-positions with respect to a heteroatom of said heteroaromatic nucleus, with an alcohol containing one or more primary or secondary alcohol groups, optionally substituted with nitro, amide, ester, halogen, cyano or (hetero)aromatic groups, using the redox couple of a triaryl- or trialkylphosphine and an azodioxo-compound at a temperature between ?40° C. and 160° C.
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- 3,4-Dialkoxypyrroles and 2,3,7,8,12,13,17,18-octaalkoxyporphyrins
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A five-step general synthesis of 3,4-dialkoxypyrroles 7c-f is described starting with the condensation of dimethyl N-benzyliminodiacetate (1 b) and diethyl oxalate to give dimethyl 1-benzyl-3,4-dihydroxypyrrole-2,5-dicarboxylate (2b), which is bis-O-alkylated to the corresponding 3,4-diethers 3c-g. Pyrrole N-benzyl cleavage followed by ester hydrolysis and decarboxylation leads to 7c-f in 10-50% overall yield. Pyrroles 7c-f react with formaldehyde or benzaldehydes to give meso-H- (8a-d) or meso-tetraaryloctaalkoxyporphyrins 9a-g in moderate yields.
- Merz,Schropp,Dotterl
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p. 795 - 800
(2007/10/02)
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