26964-93-2Relevant academic research and scientific papers
The first catalytic inverse-electron demand hetero-Diels-Alder reaction of nitroso alkenes using pyrrolidine as an organocatalyst
Wabnitz, Tobias C.,Saaby, Steen,Jorgensen, Karl Anker
, p. 828 - 834 (2004)
The first catalytic inverse-electron demand hetero-Diels-Alder reaction of nitroso alkenes has been developed. Nitroso alkenes were generated in situ from α-halooximes and underwent [4 + 2]-cycloadditions with enamines as dienophiles formed from aldehydes and pyrrolidine (10 mol%) as an organocatalyst, The presence of a suitable heterogeneous buffer system was found to be essential and best results were obtained with sodium acetate trihydrate. The resulting 5,6-dihydro-4H-oxazines were obtained in moderate to good yields under mild reaction conditions. A catalytic cycle has been proposed and evidence for the cycloaddition mechanism has been obtained. Moderate asymmetric induction (42% ee) was observed when a chiral secondary amine was used.
