Stizolobinic acid

Several cases warrant special mention. As an example, ring opening, hydrogenation, and subsequent transformations of the 5(47/)-oxazolone 459 derived from 2,3-dihydroxy-4-methoxybenzaldehyde affords a biomimetic synthesis of racemic stizolobinic acid 463 as shown in Scheme 7.151. ... 

This hypothesis is strongly supported by the presence of stizolobinic acid IS (Scheme 2 and Figure 5) in plant extracts.15 An isomer of... 

Stizolobinic acid 15 has been formally proposed as a biosynthetic precursor to acromelic acid A 520 and, importantly, radiolabeling studies have shown that it is derived biosynthetically from L-dopa.21... 

The chemical viability of the L-dopa diol cleavage process involved in the generation of the acromelic acid C-4 substituents has been examined in a biomimetic sense by Baldwin s group in syntheses of stizolobic acid 16,22 3-(6-carboxy-2-oxo-4-pyridyl)alanine 17,22 and stizolobinic acid 1523 (Figure 5). 

An analogous biomimetic route to stizolobinic acid 15, the biosynthetic side chain precursor to acromelic acid A 5, was also carried out.23 Iron(III)-catalyzed peracetic acid cleavage of the catechol portion of 23 gave alanyl muconic acid 24 which was cyclized and concomitantly deprotected to (i)-stizolobinic acid 15 (Scheme 5). Use of Schollkopf bislactim ether methodology26 also allowed the formation of enan-tiomerically pure 15 by an analogous route. 

Stizolobinic acid (= 2-Amino- 3-(6-carboxy-2-oxo-2H-pyran- 4-yl) propanoic acid)... 

Saito, K. and A Komamiiiei978. Biosynthesis of stizolobic and stizolobinic acids ZdlschnjifurNoMrforschimgy C-. 793—795. 

Metabolism 3,4-D. is formed from tyrosine by means of tyrosine 3-monooxygenase (EC 1.14.16.2.) and tet-rahydrobiopterin. DOPA is a biosynthetic precursor of dopamine, noradrenaline, and adrenaline. It is used for therapy of Parkinson s disease (dopamine deficiency). Oxidation and subsequent polymerization lead to the formation of melanins. Extradiol cleavage of the benzene ring gives rise to betalamic acid, " stizolobic acid, stizolobinic acid, muscaflavin, etc. 3,4-D. is toxic for the development of certain insects and for the reproduction of the duckweed Lemna minor. ... 

The alternative extradiol cleavage which breaks bond b in L-DOPA (172) can leaci via the intermediate (183) to muscaflavin (180) 688) and to stizolobinic acid (185), a known constituent of A. pantherina 168). The incorporation of radioactively labelled L-DOPA into stizolobinic acid in A. pantherina 553) and the co-occurrence of L-DOPA with muscaflavin in fruit bodies of Hygrocybe conica 619) add support to this 2,3-dioxygenase pathway. 

Saito, K., A. Komamine, and S. Senoh Further Studies on the Biosynthesis of Stizolobinic Acid and Stizolobic Acid in the Etiolated Seedlings of Stizolobium hass-joo. Z. Naturforsch. 31c, 15 (1976). 

The 0- and iV-hyterocyclic compounds muscaflavin, stizolobinic acid, stizolobic acid, and (S)-betalamic acid shown in Fig. 291 are derived from l-DOPA. The 0-heterocyclic derivatives contain still the L-alanyl side chain. 

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