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Differentiation of isomeric 1,2‐dihydroisoquinolin‐4(3 H )‐ones by proton magnetic resonance of their 4‐benzyl derivatives
Author(s) -
Waigh Roger D.
Publication year - 1980
Publication title -
organic magnetic resonance
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0030-4921
DOI - 10.1002/mrc.1270130422
Subject(s) - substituent , chemistry , proton magnetic resonance , reagent , group (periodic table) , medicinal chemistry , proton , stereochemistry , nuclear magnetic resonance , organic chemistry , physics , quantum mechanics
Reaction of a 3,3‐dimethyl‐1,2‐dihydroisoquinolin‐4(3 H )‐one with a benzyl Grignard reagent gives a 4‐benzyltetrahydroisoquinoline in which the signal of a 6‐methoxy group suffers a large upfield shift in the 1 H NMR spectrum, whereas a 7‐methoxy group is relatively unaffected. This effect can be used to determine whether an RO‐substituent is in the 6‐ or 7‐position and, in particular, to distinguish isomeric derivatives with different RO‐groups in the 6‐ and 7‐positions. The method will allow the mechanism of cyclization of 3,4‐dimethoxybenzylaminoacetonitriles to be more fully elucidated.