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Synthesis and reactions of 1‐[1‐oxido‐2‐(3,4)‐pyridinyl]‐2‐methyloxiranes with nitrogen nucleophiles
Author(s) -
Avasthi Kamlakar,
Knaus Edward E.
Publication year - 1981
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.5570180230
Subject(s) - chemistry , diastereomer , nucleophile , piperidine , intramolecular force , medicinal chemistry , substituent , deoxygenation , vicinal , stereochemistry , organic chemistry , catalysis
Reaction of 2(3,4)‐pyridinecarboxaldehydes (5) with ethylidenetriphenylphosphorane afford a mixture of stereoisomers Z ‐( 6 ) and E ‐1‐[2(3,4)‐pyridinyl]‐1‐propenes ( 7 ). m ‐Chloroperbenzoic acid oxidation of 6 and 7 yields a 60:40 mixture of Z ‐( 8 ) and E‐1‐[1‐oxido‐2(3,4)‐pyridinyl]‐2‐methyloxiranes ( 9 ). The regiospecific reaction of Z ‐isomers 8a‐c with cyclic amines as piperidine give rise to threo ‐1‐hydroxy‐1‐[1‐oxido‐2(3,4)‐pyridinyl]‐2‐(1‐piperidino)propanes ( 10 ) while the E ‐isomer 9a yields erythro ‐ 11 . On tho other hand, the E ‐isomers 9b and 9c having 1‐oxido‐3(4)‐pyridinyl substituents afford erythro ‐ 12 resulting from attack by piperidine at C‐1 of the oxirane. Reductive deoxygenation using 10% palladium on charcoal and hydrogen gas effectively removed the N ‐oxide substituent from the threo ‐ 10 and erythro ‐ 11 β‐aminoalcohols. Dilute solution ir spectroscopy indicated the existance of strong intramolecular hydrogen bonding in the β‐aminoalcohols 10 and 11 . The assignment of relative configuration of diastereoisomers 10 and 11 was based on the magnitude of the vicinal coupling constant J where J threo is greater than J erythro.