Rearrangement of isoxazoline-5-spiro derivatives. Part 10. Regioselective nitrone cycloadditions to methoxycarbonylmethylenecyclopropane: Synthesis of precursors of (±)-Lupinine, (±)-Epilupinine and (±)-Elaeokanine A
摘要:
The cycloaddition of cyclic nitrones to methoxycarbonylmethylenecyclopropane (1) gives adducts having the methoxycarbonyl group on C4 of the isoxazolidine ring with high regioselectivity. The thermal rearrangement of the adducts gives quinolizidinone 6 and indolizidinones 8 bearing the methoxycarbonyl group selectively at C-1 and at C-8, respectively. The two compounds are intermediates for new formal syntheses of the alkaloids (+/-)-Lupinine and (+/-)-Epilupinine, and (+/-)-Elaeokanine A, respectively.
Rearrangement of isoxazoline-5-spiro derivatives. Part 10. Regioselective nitrone cycloadditions to methoxycarbonylmethylenecyclopropane: Synthesis of precursors of (±)-Lupinine, (±)-Epilupinine and (±)-Elaeokanine A
摘要:
The cycloaddition of cyclic nitrones to methoxycarbonylmethylenecyclopropane (1) gives adducts having the methoxycarbonyl group on C4 of the isoxazolidine ring with high regioselectivity. The thermal rearrangement of the adducts gives quinolizidinone 6 and indolizidinones 8 bearing the methoxycarbonyl group selectively at C-1 and at C-8, respectively. The two compounds are intermediates for new formal syntheses of the alkaloids (+/-)-Lupinine and (+/-)-Epilupinine, and (+/-)-Elaeokanine A, respectively.