4 Pyrrolnitrinの全合成

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Total synthesis of Pyrrolnitrin (I), an antibiotic from Pseudomonas pyrocinia, was achieved by several different routes. At first, a key intermediate (IIIa) was prepared by the introduction of a methyl group to the α-position of the pyrrole (Va), Paal Knorr condensation of the 2,5-hexanedione (XII) and the introduction of two methyl groups to the pyrrole (XIV). The second type of key intermediates, β-aryl-5-methyl-2-pyrrolecarboxylic esters (XXXI and II), were synthesized from pyrroles, XIV, XXIII and XX, mainly by the methylation or methoxycarbonylation to the α-position. And the third type of key intermediates, 3-aryl-2,5-pyrroledicarboxylic esters, XXVIa, b, d, were synthesized by the introduction of the ethoxycarbonyl group to the pyrrole (XX), and by the condensation of the arylglyoxals (XXIVb, d) with dimethyl acetyliminodiacetate (XXV). The α,α'-disubstituted-3-arylpyrroles, IIIa, XXI and XXVIa, thus prepared, were transformed to Pyrrolnitrin (I) by chlorination with SO_2Cl_2, hydrolysis and decayboxylation. It was also found that 3-arylpyrrolecarboxylic esters, XLI, XLV, XXXIXa, XLVII and XLVI, were transformed directly to I by the treatment with conc. H_2SO_4. And in the course of the synthetic research, a new method of pyrrole ringclosure was developed: nitro-chlorophenylpyruvates (VIIIa and XVIII) and the nitro-chlorophenylacetone (Xa) were condensed with aminoacetal (XIII) to give pyrroles, XIV, XX and XXIII. And Hantzsch reaction was extended also to give the pyrrole (XIV).
天然有機化合物討論会の論文
1968-09-20

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