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Tri‐ and Tetrasubstituted N ‐Phthalimidoaziridines in 1,3‐Dipolar Cycloaddition Reactions
Author(s) -
Ushkov Alexander V.,
Kuznetsov Mikhail A.,
Linden Anthony,
Heimgartner Heinz
Publication year - 2010
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.200900466
Subject(s) - chemistry , dimethyl acetylenedicarboxylate , cycloaddition , isomerization , diastereomer , aziridine , adduct , azomethine ylide , medicinal chemistry , stepwise reaction , thiazolidine , 1,3 dipolar cycloaddition , stereochemistry , ring (chemistry) , organic chemistry , catalysis , kinetics , reaction rate constant , physics , quantum mechanics , order of reaction
The thermal reactions of the 2,2,3‐trisubstituted N ‐phthalimidoaziridine 1a with dimethyl acetylenedicarboxylate (DMAD), thioketones 4a – 4d , and dimethyl azodicarboxylate ( 5 ) proceed even at room temperature leading to the five‐membered cycloadducts 2a, 6 – 8 , and 12 , respectively, with retention of the spatial arrangement of the aziridine substituents, in contrast to the expectation based on the conservation of orbital symmetry in concerted reactions. The analogous reactions of the tetrasubstituted phthalimidoaziridine 1b with thioketones at 40° lead to the 1,3‐thiazolidine derivatives 10 and 11 as mixtures of diastereoisomers. These unexpected results may be explained by either the isomerization of the intermediate azomethine ylides or a non‐concerted stepwise cycloaddition reaction of these ylides with the dipolarophiles. The structures of some adducts have been determined by X‐ray crystallography.