865775-40-2Relevant academic research and scientific papers
Synthesis of optically active heterocyclic compounds by preparation of 1,3-dinitro derivatives and enzymatic enantioselective desymmetrization of prochiral diamines
Rios-Lombardia, Nicolas,Busto, Eduardo,Gotor-Fernandez, Vicente,Gotor, Vicente
experimental part, p. 484 - 493 (2010/04/28)
A general approach for the highly efficient chemical preparation of novel optically active 2-substituted propane-1,3-diamines is described. Diamines have been obtained from the corresponding commercially available aldehydes in a straightforward, two-step synthesis via the corresponding 1,3-dinitro compounds, which were hydrogenated under mild reaction conditions by using platinum dioxide as the catalyst. Subsequent enzymatic enantioselective desymmetrization mediated by Pseudomonas cepacia lipase allowed the recovery of a family of monocarbamates in good to high, enantiomeric excesses (70-90% ee).
Refined synthesis of 2,3,4,5-tetrahydro-1,3,3-trimethyldipyrrin, a deceptively simple precursor to hydroporphyrins
Ptaszek, Marcin,Bhaumik, Jayeeta,Kim, Han-Je,Taniguchi, Masahiko,Lindsey, Jonathan S.
, p. 651 - 659 (2012/12/25)
2,3,4,5-Tetrahydro-1,3,3-trimethyldipyrrin (1) is a crucial building block in the rational synthesis of chlorins and oxochlorins. The prior five-step synthesis of 1 from pyrrole-2-carboxaldehyde (2) employed relatively simple and well-known reactions yet suffered from several drawbacks, including limited scale (≤0.5 g of 1 per run). A streamlined preparation of 1 has been developed that entails four steps: (i) nitro-aldol condensation of 2 and nitromethane under neat conditions to give 2-(2-nitrovinyl)pyrrole (3), (ii) reduction of 3 with NaBH4 to give 2-(2-nitroethyl)pyrrole (4), (iii) Michael addition of 4 with mesityl oxide under neat conditions or at high concentration to give γ-nitrohexanone-pyrrole 5, and (iv) reductive cyclization of 5 with zinc/ammonium formate to give 1. Several multistep transformations have been established, including the direct conversion of 2 → 1. The advantages of the new procedures include (1) fewer steps, (2) avoidance of several problematic reagents, (3) diminished consumption of solvents and reagents, (4) lessened reliance on chromatography, and (5) scalability. The new procedures facilitate the preparation of 1 at the multigram scale.
