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Ring opening reaction of 1,2‐diaryl‐3‐methyl‐1,4,5,6‐tetrahydropyrimidinium salts with metal hydride complexes
Author(s) -
Maso MÓNica Dal,
Orelli Liliana,
Perillo Isabel A.
Publication year - 1994
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570310104
Subject(s) - chemistry , hydride , aluminum hydride , iminium , aminal , borohydride , medicinal chemistry , salt (chemistry) , lithium (medication) , ring (chemistry) , borane , hydrolysis , metal , lithium aluminium hydride , alkaline hydrolysis , organic chemistry , ion , catalysis , medicine , endocrinology , methoxide
The reaction of a series of 1,2‐diaryl‐3‐methyl‐1,4,5,6‐tetrahydropyrimidinium iodides 1 with reducing agents acting by hydride ion transfer was studied. With excellent yields alkaline borohydrides readily reacted to form N' ‐aryl‐ N ‐benzyl‐ N ‐methyltrimethylenediamines 3 by reductive cleavage of the intermediate hexahydropyrimidine 2 . Ring opening is explained by the formation of a stabilized iminium ion, which also accounts for the cyclic aminal 2 hydrolysis observed in alcoholic solution after gradual addition of borohydride. Reactions with lithium aluminum hydride or with borane failed to render satisfactory results due to insolubility of the salt in solvents commonly employed. Comparisons are made with the behaviour of 1 H ‐4,5‐dihydroimidazolium salts which were studied in an earlier paper.