New Insight into the Azaenamine Behaviour of N-Arylhydrazones: First Aldol and Improved Mannich Reactions with Unactivated Aldehydes

Synlett

Volumn , Issue 12, 2003, Pages 1844-1846

  Kaïm, Laurent El ^a   Gautier, Laurent ^a   Grimaud, Laurence ^a   Michaut, Valerie ^a  

^a Ecole Nationale Superieure de Techniques Avancees   (France)

Author keywords

Azo compounds; Cyclo additions; Hydrazones; Mannich bases

Indexed keywords

ALDEHYDE DERIVATIVE; AZAENAMINE; ENAMINE; HETEROCYCLIC COMPOUND; HYDRAZONE DERIVATIVE; SOLVENT; UNCLASSIFIED DRUG;

ALDOL REACTION; ARTICLE; DIASTEREOISOMER; ELECTRON TRANSPORT; MANNICH REACTION; MICHAEL ADDITION; OXIDATION; REACTION ANALYSIS;

EID: 0142060646     PISSN: 09365214     EISSN: None     Source Type: Journal    
DOI: None     Document Type: Article

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21. These α-ketohydrazones are very easily prepared by diazonium coupling with β-ketoesters followed by decarboxylation (Japp-Klingemann reaction).
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25. Typical experimental procedure for the Mannich process in diethylamine: To a solution of hydrazone 1g (1 mmol) in diethylamine (1 mL) was added benzaldehyde (2 mmol) and the mixture refluxed until completion. Evaporation of the solvent afforded the crude product which was directly treated with 1-dodecanthiol in chlorobenzene (4 h, reflux) to form the new thioether 7 in 56% isolated yield. Typical experimental procedure for the aldol reaction: To a solution of hydrazone 1g (1 mmol) in diisopropylamine (1 mL) was added benzaldehyde (2 mmol) and the mixture refluxed until completion. Evaporation and separation on silica gel afforded the expected aldol adduct 6a in 70% isolated yield.