Massenspektrometrische Untersuchungen an Benzylisochinolinen: Elektronenstoßinduzierte Abspaltung der Substituenten am Benzylrest

Abstract

Das Fragmentierungsverhalten der 4-Benzylisochinoline 2-8 nach Elektronenstofi-Ionisation wird beschrieben und mit dem der entsprechenden 1-Benzylisochinoline 1 verglichen. Der Verlust des o-standigen Benzylsubstituenten X in den Isochinolinen 3-8 fiihrt zu Signalen mittlerer bis hoher Intensitat. Eine eindeutige Unterscheidung zwischen den ortho-und meta-/para-Isomeren 5a-c/7a-c ist nur bei hohen Anregungsenergien moglich. Mass Spectrometric Studies on Benzylisoquinolines: Electron Jmpact Jnduced Loss of the Benzyl SubstituentsThe modes of electron-impact induced fragmentation of the 4-benzylisoquinolines 2-8 are reported and compared with those of the isomeric I-benzylisoquinolines 1. Loss of the ortho substituents X in 3-8 gives rise to signals of medium to high intensities. High ionization energies make it possible to differentiate unequivocally between the ortho and meta/para isomers 5a-c/7a-c.

Condensation-Based Methods for the C–H Bond Functionalization of Amines

“…The intermediacy of enamine 23 was established by Sainsbury 19 and Dannhardt. 20 In addition, indirect evidence for the existence of azomethine ylide 19 was obtained by Dannhardt by trapping this intermediate in a (3+2) dipolar cycloaddition with benzaldehyde. 21 An alternative scenario involving azomethine ylide 27 cannot be ruled out but appears less likely in light of computational studies on related systems (vide infra).…”

“…Condensation of THIQ and benzaldehyde in the presence of benzoic acid first results in the formation of N,O-acetal 18. This species undergoes isomerization to N,O-acetal 20 This document was downloaded for personal use only. Unauthorized distribution is strictly prohibited.…”

Redox‐Neutral Aromatization of Cyclic Amines: Mechanistic Insights and Harnessing of Reactive Intermediates for Amine α‐ and β‐C−H Functionalization

“…These rather unusual transformations are often facilitated by carboxylic acids and are amongt he oldest reactions that result in the functionalization of relativelyu nreactive CÀHb onds in a-, b-, and g-positions of an amine nitrogen atom (Scheme 1). [1][2][3][4][5][6][7] Reactions in which pyrroles are formed from pyrrolidineo rp yrroline, or indole from indoline, represent redox-neutral transformations. No external oxidantsa re required, and water is produced as the sole byproduct.…”