Pyrroles 3- hydroxy- from

Another important example of the Michael addition in biochemistry and molecnlar biology is the reaction of 4-hydroxynon-2-enal with amines and snlfydryl gronps (Winter, C.K., Segall, H.J., and Haddon, W.F., Formation of cyclic addncts of deoxygnanosine with the aldehyde trans-4-hydroxy-2-hexenal and fran.y-4-hydroxy-2-nonenal in vitro. Cancer Res. 46, 5682-5686, 1986 Sayre, L.M., Arora, P.K., Iyer, R.S., and Salomon, R.G., Pyrrole formation from 4-hydroxynonenal and primary amines, Chem. Res. Toxicol. 6, 19-22, 1993 Hartley, D.P, Ruth, J.A., and Petersen,... 

In the reaction of ethyl cyanoacetate with sulphur and base, 2,4-diamino-3,S-di(ethoxycarbonyl)thiophen was only the minor product (20%). The major products were pyrrole derivatives. From cyanoacetamide and benzyl cyanide no thiophen derivatives were obtained. The reaction of (9a) with (10) in the presence of triethylamine yields the aminothiophen (11), while (9b) gives the hydroxy thiophen (12). If the salt of ethyl (thiobenzoyl)... 

Hydroxy-THISs react with electron-deficient alkynes to give nonisol-able adducts that extrude carbonyl sulfide, affording pyrroles (23). Compound 16 (X = 0) seems particularly reactive (Scheme 16) (25). The cycloaddition to benzyne yields isoindoles in low- yield. Further cyclo-addition between isoindole and benzyne leads to an iminoanthracene as the main product (Scheme 17). The cycloadducts derived from electron-deficient alkenes are stable (23, 25) unless highly strained. Thus the two adducts, 18a (R = H, R = COOMe) and 18b (R = COOMe, R = H), formed from 7, both extrude furan and COS under the reaction conditions producing the pyrroles (19. R = H or COOMe) (Scheme 18). Similarly, the cycloadduct formed between 16 (X = 0) and dimethylfumarate... 

Pyrrole, 3-hydroxy-geometry, 4, 158 synthesis, 4, 343 tautomerism, 4, 36, 198 Pyrrole, 3-([Pg.816]

Pyrrole nucleus, in basicity scale, 71 as model in resonance theory. 69 Pyrroles, from 5-acylamino-THlSs. 14 from 5-hydroxy-THISs, 9 from 4-substituted-5-hydroxythiazoles,... 

Two syntheses of the pyrrole derivative detoxinine and a part of the natural depsipeptide detoxin are described. In each, the formation of detoxinine takes place from bicyclic system 74, obtained in a multistep transformation from A-protected 3-hydroxy- or 4-iodoproline (83LA982 90CC1240). 

The attachment of the pyrrole ring at C-8 was confirmed by noting that the shift of the aromatic H in the H-NMR spectrum moved from 8 5.93 to 6.38 in the acetylated product. This showed that the free proton is ortho to the phenolic OH at C-5 and that the pyrrole must therefore be at C-8. Further proof of the structure of vochysine was obtained when it was synthesized from 5,4 -di-hydroxy-7-methoxyflavan and an alcoholic solution of pyrroline. 

Although the hydroxy group is a relatively poor leaving group, its base-catalyzed nucleophilic substitution by the mechanism shown in Scheme 69 accounts not only for the hydrogenolysis of the 3-hydroxymethylindoles, but also for their SN reactions with ethoxide ions, cyanide ions and with piperidine. Nucleophilic substitution on 2-hydroxymethyl-pyrroles is generally precluded by the faster formation of the bis(2-pyrrolyl)methanes, but the synthesis of 2-cyano-2-(2,5-dimethyl-3-pyrroIyl) propanes from 2,5-dimethylpyrrole, propanone and potassium cyanide probably results from an SN reaction of the cyanide ion upon the initially formed 3-pyrrolylcarbinol (81USP4248784). The formation of (294)... 

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