We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
1,3-Dipolar Cycloadditions of (4R*,5R*)-1-Arylmethylidene- 4-benzamido-3-oxo-5-phenylpyrazolidin-1-ium-2-ides to Di-(-)-menthyl Maleate.
- Authors
Pezdirc, Lidija; Bevk, David; Pirc, Samo; Svete, Jurij
- Abstract
1,3-Dipolar cycloadditions of racemic (1Z,4R*,5R*)-arylmethylidene-4-benzamido-5-phenyl-3-pyrazolidinon-1-azomethine imines 3 to enantiopure di-(-)-menthyl maleate (4) afforded mixtures of diastereomeric cycloadducts 5/5′-7/7′. Selectivity as well as stereochemistry of cycloadditions were dependent on the substituents at the 1′-Ar residue of dipoles 3. Thus, reactions of dipoles 3a-j with at least one free ortho-position gave either di-(-)-menthyl (1R*,2S*,3R*,5R*,6R*)-3-aryl-6-benzamido-7-oxo-5-phenylhexahydropyrazolo[1,2-a]pyrazole-1,2-dicarboxylates 5/5' (the endo-isomers) and/or di-(-)-menthyl (1S*,2R*,3R*,5R*,6R*)-3-aryl-6-benzamido-7-oxo-5-phenylhexahydropyrazolo[ 1,2-a]pyrazole-1,2-dicarboxylates 6/6′ (the exo-isomers) with syn-oriented 3-H and 5-H, whilst reactions of 4 with ortho-disubstituted dipoles 3k,l gave (1S*,2R*,3S*,5R*,6R*)-diastereomers 7/7′k,l with anti-oriented 3-H and 5-H. Separation of diastereomeric cycloadducts 5/5′-7/7′ by crystallization and/or MPLC furnished isomerically pure compounds 5a,b,d,g, 5′b,d,h, 6c,d,j, and 6′c,d,f and purified mixtures of diastereomers 5/5′e, 6/6′e,h, and 7/7′k,l in 1-42% yields. The relative configuration of the pyrazolo[1,2-a]pyrazolone structural element in the products 5/5′-7/7′ was determined by NMR.
- Subjects
RING formation (Chemistry); PYRAZOLONES; STEREOCHEMISTRY; CRYSTALLIZATION; MAGNETIC dipoles; CHEMICAL reactions; NUCLEAR magnetic resonance
- Publication
Acta Chimica Slovenica, 2009, Vol 56, Issue 3, p545
- ISSN
1318-0207
- Publication type
Article