Pyrrole, pyrrolidine

To probe interactions between active silanol sites and the isothiazolin-based biocides a number of model probes were investigated 12. The adsorbates (1-methylpyrro lidin-2-one, pyridine, pyrrolidine, pyrrole, 2-methylthiophene, 2-octyl-4-isothiazolin-3-one, 4,5-dichloro-2-octyl-4-isothiazolin-3-one and 2-cyclopenen-l -one,) varied in basicity, polarity and 7i-character. The amounts of the adsorbates retained by... 

An explosion occurred when benzaldehyde, pyrrolidine (pyrrole ) and propionic acid were heated to form porphins. 

Tables I through VIII summarize the occurrences of alkaloids from ants and other insects. Each table presents chemical structures as well as specific sources of particular types of alkaloids e.g.. Table I covers piperidines and pyridines. Table II, pyrrolidines, pyrroles, and indolizidines.

Pyrrole and Pyrrolidine. Pyrroles (azoles) undergo aromatic hydroxylation pyrrolidines (azolidines) undergo conjugation with either glucuronic acid or sulfuric acid. 

AMI, MP2(fc)/6-31G, and experimental IR spectra were compared by the author for 18 of the 20 compounds in Fig. 6.2 (suitable IRs were not found for HOC1 and CH3SH) and for these 10 cyclopentane, cyclopentene, cyclopentanone, pyrrolidine, pyrrole, butanone, diethyl ether, 1-butanol, 2-butanol, and tetrahydrofuran. On the basis of the relative intensities of the bands, of these 28 compounds only for six, HCN, CH3OH, H2C=CH2, HOF, cyclopentene and cyclopentanone were both the AMI and MP2 spectra similar to the experimental for the others the MP2 IRs were closer to experiment... 

PYRROLIDINE, PYRROL IZIDINE, PYRIDINE, PIPERIDINE AND QUINOLIZIDINE ALKALOIDS IN THE CONTEXT OF HPLC ANALYIS OF DRUGS OF ABUSE (CHAPTER 7)... 

Although there are many syntheses of pyrrolidines, pyrrole synthesis is not usually approached through the saturated ring. There are some examples of syntheses in which dihydropyrroles are aromatized. a-Pyrrolidinylidene acetates, for example, can be aromatized by selenylation of the enolate followed by oxidative elimination of the selenoxide (Equation (63)) <75JOC800>. 

Aromatization decreases solventbasicityby afactorof3.5-5.5, as illustrated by the following couples pyrrolidine/pyrrole (0.99/0.18), N-methylpyrrolidine/ N-ethylpyrrole (0.92/0.22), tetrahydrofuran/fean (0.59/0.11), 2-methyltetrahy-drofuran/2-methylfuran (0.56/0.16), cyclohexylamine/aniline (0.96/0.26), N-methylcyclohexylamine/N-methylaniline (0.92/0.21), N,N-dimethylcyclohexyl-amine/N,N-dmiethylaniline (0.99/0.30) and a structurally less similar couple such as piperidine/pyridine (0.93/0.58). 

Partial hydrogenation of pyrrole derivatives and partial dehydrogenation of pyrrolidines afford /I -pyrrolines (80-82). However, because of the complex nature of the reaction, it is of little preparative value. The same is true for isomerization of /) -pyrrolines to /) -pyrrolines (83). A photodehydrogenation of 2,6-dimethylpiperidine (26) has been observed recently, affording 2,6-dimethyl-3,4,5,6-tetrahydropyridine (27) in a good yield (84)-... 

Pyrrole is known to slowly undergo hydrogenation to 2,5-dihydropyrrole, which is then easily hydrogenated to pyrrolidine. 

The trimer having been produced, protonation of the central pyrrolidine nitrogen occurs, and the formal positive charge then sufficiently retards further electrophilic attack on the two pyrrole nuclei to allow the isolation of tripyrrole. 

As discussed in Chapter 6, nitro compounds are converted into amines, oximes, or carbonyl compounds. They serve as usefid starting materials for the preparation of various heterocyclic compounds. Especially, five-membered nitrogen heterocycles, such as pyrroles, indoles, ind pyrrolidines, are frequently prepared from nitro compounds. Syntheses of heterocyclic compounds using nitro compounds are described partially in Chapters 4, 6 and 9. This chapter focuses on synthesis of hetero-aromadcs fmainly pyrroles ind indolesi ind saturated nitrogen heterocycles such as pyrrolidines ind their derivadves. 

The Michael additkin of Lithium etiolates to tiitroalkenes folbwed by reaction with acetic anhydnde gives acetic niironic anhydndes, which are good precursors for 1,4-diketones, pyrroles, and pyrrolidines fEq. 10.73. ... 

---