Five-Membered 2,3-Dioxo Heterocycles: XCII. Reaction of 3-Aroyl-1H-pyrrolo[2,1-c] [l,4]benzoxazine-1,2,4-triones with Ethyl (2Z)-(3,3-Dimethyl-8-oxo-2-azaspiro[4.5]deca-6,9-dien- 1-ylidene)ethanoate. Synthesis of Bridged Analogs of Pyrrolizidine Alkaloids

摘要

3-Aroyl-1H-pyrrolo[2,1-c][1,4]benzoxazine-l,2,4-triones reacted with ethyl (2Z)-(3,3-dimethyl-8-oxo-2-azaspiro[4.5]deca-6,9-dien-l-ylidene)acetate to give ethyl 6'-aryl-2'-(2-hydroxyphenyl)-11',11'-dimethyl-3',4,4',13'-tetraoxospiro[2,5-cyclohexadiene-l,9'-(7'-oxa-2',12'-diazatetracyclo[6.5.1.01,5.08,12]tetradec-5'-ene)]-14'-carboxylates whose structure was confirmed by X-ray analysis. The products may be regarded as bridged analogs of pyrrolizidine alkaloids, 7'-oxa-2',12'-diazatetracyclo[6.5.1.0~(1,5).0~(8,12)]tetradecanes.