72053-02-2Relevant academic research and scientific papers
Enantioselective Rh-catalyzed hydrogenation of N-formyl dehydroamino esters with monodentate phosphoramidite ligands
Panella, Lavinia,Aleixandre, Alicia Marco,Kruidhof, Gerlof J.,Robertus, Jort,Feringa, Ben L.,De Vries, Johannes G.,Minnaard, Adriaan J.
, p. 2026 - 2036 (2007/10/03)
Enantioselectivities up to >99% ee were achieved in the rhodium-catalyzed asymmetric hydrogenation of N-formyl dehydroamino esters using monodentate phosphoramidites as chiral ligands. The substrates were synthesized by condensation of methyl isocyanoacetate with a range of aldehydes and with cyclohexanone. A highly convenient multigram scale one step synthesis of methyl 2-(formamido)acrylate was developed. This compound was used in the synthesis of methyl 2-(formamido)cinnamate via a solvent free Heck reaction. Moreover, full conversion and >99% ee were obtained in 1 h in the hydrogenation of methyl 2-(formamido)acrylate with 0.2 mol% catalyst and 2 bar hydrogen pressure. The versatility of the formyl protection was established by its removal under mild conditions.
(Z)-selective β-bromination of N-formyl-α,β-dehydroamino acid esters
Yamada, Masaki,Nakao, Kazuya,Fukui, Toshio,Nunami, Ken-Ichi
, p. 5751 - 5764 (2007/10/03)
Stereoselective β-bromination of N-formyl-α,β-dehydroamino acid esters 5 was investigated. A reaction of 5 with NBS afforded α-bromo-N-formylimines 10 which successively isomerized to give β-bromo-N-formyl-α,β-dehydroamino acid esters 4. The migration of the double bond of the intermediates 10 with bulky substituents at the β-position resulted in highly stereoselective formation of (Z)-4, while that of the substrates with less bulky substituents proceeded non-stereoselectively. A mechanism of the stereoselective bromination was proposed on the basis of semiempirical calculations using AM1.
