REARRANGEMENT OF ISOXAZOLINE-5-SPIRO DERIVATIVES .10. REGIOSELECTIVE NITRONE CYCLOADDITIONS TO METHOXYCARBONYLMETHYLENECYCLOPROPANE - SYNTHESIS OF PRECURSORS OF (PLUS-OR-MINUS)-LUPININE, (PLUS-OR-MINUS)-EPILUPININE AND (PLUS-OR-MINUS)-ELAEOKANINE-A

The cycloaddition of cyclic nitrones to methoxycarbonylmethylenecyclop ropane (1) gives adducts having the methoxycarbonyl group on C4 of the isoxazolidine ring with high regioselectivity. The thermal rearrangem ent of the adducts gives quinolizidinone 6 and indolizidinones 8 beari ng the methoxycarbonyl group selectively at C-1 and at C-8, respective ly. The two compounds are intermediates for new formal syntheses of th e alkaloids (+/-)-Lupinine and (+/-)-Epilupinine, and (+/-)-Elaeokanin e A, respectively.