21939-14-0

Upstream product

• 91-21-4 1,2,3,4-tetrahydroisoquinoline 
• 83-25-0 N-phenylmaleimide 
• 941-69-5 N-phenyl-maleimide 
• 22901-09-3 2-(2-bromoethyl)benzaldehyde 
• 24423-87-8 3,4-dihydro-isoquinoline 2-oxide 

Relevant academic research and scientific papers

Metal-Free Solvent Promoted Oxidation of Benzylic Secondary Amines to Nitrones with H2O2

An environmentally benign protocol for the generation of nitrones from benzylic secondary amines via catalyst-free oxidation of secondary amines using H2O2 in MeOH or CH3CN is described. This methodology provides a selective access to a variety of C-aryl nitrones in yields of 60 to 93%. Several studies have been performed to shed light on the reaction mechanism and the role of the solvent.

Cascade oxime formation, cyclization to a nitrone, and intermolecular dipolar cycloaddition

Simple haloaldehydes, including enolisable aldehydes, were found to be suitable for the formation of cyclic products by cascade (domino) condensation, cyclisation, dipolar cycloaddition chemistry. This multi-component reaction approach to heterocyclic compounds was explored by using hydroxylamine, a selection of aldehydes, and a selection of activated dipolarophiles. Initial condensation gives intermediate oximes that undergo cyclisation with displacement of halide to give intermediate nitrones; these nitrones undergo in situ intermolecular dipolar cycloaddition reactions to give isoxazolidines. The cycloadducts from using dimethyl fumarate were treated with zinc/acetic acid to give lactam products and this provides an easy way to prepare pyrrolizinones, indolizinones, and pyrrolo[2,1-a]isoquinolinones. The chemistry is illustrated with a very short synthesis of the pyrrolizidine alkaloid macronecine and a formal synthesis of petasinecine.

STERIC EFFECTS VS SECONDARY ORBITAL INTERACTIONS IN NITRONE CYCLOADDITIONS. STERIC EFFECTS IN CYCLOREVERSIONS OF ISOXAZOLIDINES.

3,4-Dihydroisoquinoline-N-oxide 1 reacted readily with both acyclic (Z)- and (E)-disubstituted alkenes bearing electron-attracting substituents (methoxycarbonyl, cyano, phenylsulphonyl and benzoyl groups) and with cyclic derivatives (e.g.) maleimides) to give mixtures of the two possible diastereoisomers.Similar amounts of endo- and exo-adducts were formed in the reactions of (Z)-cyano, methoxycarbonyl and benzoyl derivatives whereas exo-addition clearly won over its endo-counterpart in the case of (Z)-(phenylsulphonyl) and cyclic derivatives.High exo-selectivity was also observed in the sluggish reactions of 1 with electron-rich alkenes .Our results, which revise previous literature data, clearly show that an "endo-rule" does not hold for the reactions of 1 with (Z)-1,2-disubstituted alkenes.We conclude that in these reactions repulsive steric interactions either counteract efficiently or clearly win over stabilizing secondary orbital overlaps in controlling endo/exo-selectivity.These reactions were found reversible under mild conditions so that relative formation rates of related pairs of (Z)- and (E)-dipolarophiles in cycloreversion processes of isoxazolidines could be determined; as a rule (E)-alkenes are extruded faster than (Z)-isomers.These results provide unambiguous experimental evidence that increase in steric compression between the substituents in (Z)-alkenes, on their way toward transition state, is not a major factor in determining their lower reactivity with respect to (E)-isomers in 1,3-dipolar cycloadditions.