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Dicarboxylates of 3‐Methylidene‐β‐lactams: Addition Reactions to the Exocyclic Double Bond, Formation of Spiro‐β‐lactams, and Reductive Ring Opening by Hydrazines
Author(s) -
Gürtler Susanne,
Johner Michael,
Ruf Sabine,
Otto HansHartwig
Publication year - 1993
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19930760820
Subject(s) - chemistry , double bond , nucleophile , cyclopropane , azetidine , ring (chemistry) , hydrazine (antidepressant) , steric effects , lactam , nucleophilic addition , medicinal chemistry , stereochemistry , adduct , organic chemistry , chromatography , catalysis
O‐, S‐, and N‐Nucleophiles are added to the exocyclic double bond of the title compounds 1 . The addition of O‐ or S‐nucleophiles yields stable products ( Scheme 1 ), while addition of N‐nucleophiles results in thermally labile compounds ( Scheme 2 ). The reaction is studied by spectroscopic methods. From hydrazine adducts, a spiro[azetidine‐3,3′‐pyrazolidine] 7 is obtained, and the addition products of methyl‐ and benzylhydrazine rearrange to pyrazol‐4‐carboxylates 6 . Furthermore, the exocyclic double bond is used for the formation of spiro‐β‐lactams either by cyclopropane formation or by Diels‐Alder reactions ( Scheme 4 ). The steric course of all reactions is studied, and it is shown that all reactions with the double bond occur from the side opposite to the bulkier substitutent at C(4) of the β‐lactam ring.