153933-58-5Relevant articles and documents
Divergent reactivity of homologue ortho-Allenylbenzaldehydes controlled by the tether length: Chromone versus chromene formation
Alcaide, Benito,Almendros, Pedro,Fernndez, Israel,Del Campo, Teresa Martnez,Naranjo, Teresa
, p. 1533 - 1541 (2015/01/30)
The divergent behavior of two homologue allenals, namely, 2-(buta-2,3-dienyloxy)- and 2-(propa-1,2-dienyloxy)benzaldehydes, as cyclization substrates is described. 2-(Buta-2,3-dienyloxy)benzaldehydes suffers a formal allenic carbocyclization reaction to afford chromenes, whereas 2-(propa-1,2-dienyloxy)benzaldehydes react to yield chromones. The formation of chromenes is strictly a formal hydroarylation process divided into two parts, namely, allenic Claisen-type rearrangement and oxycyclization. An unknown N-heterocyclic carbene (NHC)-catalyzed allenic hydroacylation reaction must be invoked to account for the preparation of chromones. ortho-Allenylbenzaldehydes bearing either electron-donating substituents or electron-withdrawing substituents worked well to afford both the hydroarylation and hydroacylation products. This unexpected difference in reactivity can be rationalized by means of density functional theory calculations.
Synthesis of novel bicyclic nitrogen heterocycles by the intramolecular dipolar cycloaddition reaction of nitrones with allenes and alkynes
Padwa, Albert,Meske, Michael,Ni, Zhijie
, p. 89 - 106 (2007/10/02)
A study of the intramolecular dipolar cycloaddition reactions of a series of allenyl and alkynyl nitrones has been carried out. Phenylhydroxylamine readily reacts with o-(1,2-propadienyloxy)benzaldehyde to give a dioxaazabicyclo[3.2.1]octene. The intramol
