CONTENTS
ix
10 Nucleophilic reactions involving enolate anions
347
10.1 Enols and enolization
347
10.1.1
Hydrogen exchange
351
10.1.2
Racemization
352
10.1.3
Conjugation
354
10.1.4
Halogenation
356
10.2 Alkylation of enolate anions
357
10.3 Addition–dehydration: the aldol reaction
360
10.4 Other stabilized anions as nucleophiles: nitriles and nitromethane
365
10.5 Enamines as nucleophiles
366
10.6 The Mannich reaction
369
10.7 Enolate anions from carboxylic acid derivatives
372
10.8 Acylation of enolate anions: the Claisen reaction
379
10.8.1
Reverse Claisen reactions
386
10.9 Decarboxylation reactions
387
10.10 Nucleophilic addition to conjugated systems: conjugate addition
and Michael reactions
393
11 Heterocycles
403
11.1 Heterocycles
403
11.2 Non-aromatic heterocycles
403
11.3 Aromaticity and heteroaromaticity
405
11.4 Six-membered aromatic heterocycles
407
11.4.1
Pyridine
407
11.4.2
Nucleophilic addition to pyridinium salts
414
11.4.3
Tautomerism: pyridones
416
11.4.4
Pyrylium cation and pyrones
418
11.5 Five-membered aromatic heterocycles
420
11.5.1
Pyrrole
420
11.5.2
Furan and thiophene
426
11.6 Six-membered rings with two heteroatoms
427
11.6.1
Diazines
427
11.6.2
Tautomerism in hydroxy- and amino-diazines
429
11.7 Five-membered rings with two heteroatoms
432
11.7.1
1,3-Azoles: imidazole, oxazole, and thiazole
432
11.7.2
Tautomerism in imidazoles
433
11.7.3
Reactivity of 1,3-azoles
436
11.7.4
1,2-Azoles: pyrazole, isoxazole, and isothiazole
438
11.8 Heterocycles fused to a benzene ring
438
11.8.1
Quinoline and isoquinoline
440
11.8.2
Indole
443
11.9 Fused heterocycles
448
11.9.1
Purines
449
11.9.2
Pteridines
452
11.10 Some classic aromatic heterocycle syntheses
457
11.10.1 Hantzsch pyridine synthesis
458
11.10.2 Skraup quinoline synthesis
458
ix
10 Nucleophilic reactions involving enolate anions
347
10.1 Enols and enolization
347
10.1.1
Hydrogen exchange
351
10.1.2
Racemization
352
10.1.3
Conjugation
354
10.1.4
Halogenation
356
10.2 Alkylation of enolate anions
357
10.3 Addition–dehydration: the aldol reaction
360
10.4 Other stabilized anions as nucleophiles: nitriles and nitromethane
365
10.5 Enamines as nucleophiles
366
10.6 The Mannich reaction
369
10.7 Enolate anions from carboxylic acid derivatives
372
10.8 Acylation of enolate anions: the Claisen reaction
379
10.8.1
Reverse Claisen reactions
386
10.9 Decarboxylation reactions
387
10.10 Nucleophilic addition to conjugated systems: conjugate addition
and Michael reactions
393
11 Heterocycles
403
11.1 Heterocycles
403
11.2 Non-aromatic heterocycles
403
11.3 Aromaticity and heteroaromaticity
405
11.4 Six-membered aromatic heterocycles
407
11.4.1
Pyridine
407
11.4.2
Nucleophilic addition to pyridinium salts
414
11.4.3
Tautomerism: pyridones
416
11.4.4
Pyrylium cation and pyrones
418
11.5 Five-membered aromatic heterocycles
420
11.5.1
Pyrrole
420
11.5.2
Furan and thiophene
426
11.6 Six-membered rings with two heteroatoms
427
11.6.1
Diazines
427
11.6.2
Tautomerism in hydroxy- and amino-diazines
429
11.7 Five-membered rings with two heteroatoms
432
11.7.1
1,3-Azoles: imidazole, oxazole, and thiazole
432
11.7.2
Tautomerism in imidazoles
433
11.7.3
Reactivity of 1,3-azoles
436
11.7.4
1,2-Azoles: pyrazole, isoxazole, and isothiazole
438
11.8 Heterocycles fused to a benzene ring
438
11.8.1
Quinoline and isoquinoline
440
11.8.2
Indole
443
11.9 Fused heterocycles
448
11.9.1
Purines
449
11.9.2
Pteridines
452
11.10 Some classic aromatic heterocycle syntheses
457
11.10.1 Hantzsch pyridine synthesis
458
11.10.2 Skraup quinoline synthesis
458