Pyrroles and derivatives

Imines also form adducts with B(C6F5)3, and Erker et al.144 and Resconi and coworkers136 have used this to clever advantage in preparing a new family of Bronsted acids comprised essentially of the B(C6F5)3 adducts of the thermodynamically less stable tautomers of pyrrole and derivatives (Entries 21 and 22, Scheme 20). Erker s preparation of the compound relies on protonation of the lithium pyrrolyl borate with HC1 Resoni has... 

Calix[4]pyrrole and derivatives involved in this chapter are those receptors which are able to recognise selectively the fluoride anion in solution. It is shown that the fluoride anion binding ability of these receptors can be tuned. 

Pyrroles generally have an intense and unpleasant odour, but the odour of some pyrroles and derived compounds resembles caramel, nuts, bread or chocolate upon dilution. A non-volatile pyrrole derivative is 5-oxopyrroHdine-2-carboxyHc acid, produced by heating glutamic acid or glutamine. 

CH3COCH2CH1COCH3. Colourless liquid which becomes yellow on standing b.p. I9PC. Obtained by boiling 2,5-dimethylfuran with dilute sulphuric acid. It readily condenses with a variety of substances to give derivatives of furan, thiophen and pyrrole, and is a solvent for cellulose acetate. 

See also g-Aminobutyric acid.) PYRROLE AND PYRROLE DERIVATIVES] (Vol 20)... 

Except for the pyrroHdinones (see Pyrrole and pyrrole derivatives), these products are discussed in the following. 

When heated with acidic oxide catalysts, mixtures of butynediol with ammonia or amines give pyrroles (66) (see Pyrrole AND PYRROLE DERIVATIVES). 

The dipole moment varies according to the solvent it is ca 5.14 x 10 ° Cm (ca 1.55 D) when pure and ca 6.0 x 10 ° Cm (ca 1.8 D) in a nonpolar solvent, such as benzene or cyclohexane (14,15). In solvents to which it can hydrogen bond, the dipole moment may be much higher. The dipole is directed toward the ring from a positive nitrogen atom, whereas the saturated nonaromatic analogue pyrroHdine [123-75-1] has a dipole moment of 5.24 X 10 ° C-m (1.57 D) and is oppositely directed. Pyrrole and its alkyl derivatives are TT-electron rich and form colored charge-transfer complexes with acceptor molecules, eg, iodine and tetracyanoethylene (16). 

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