α-Acylamino radical cyclizations using allenes and vinylsilanes as addends: applications to the synthesis of (+)-heliotridine and (-)-dihydroxyheliotridine
作者:Jeffrey M. Dener、David J. Hart
DOI:10.1016/s0040-4020(01)86072-5
日期:1988.1
Total syntheses of the pyrrolizidine bases (+)-heliotridine (4) and (-)-dihydroxyheliotridane (5) from (S)-3-acetoxysuccinimide are described. The syntheses of 4 and 5 revolve around free radical cyclizations involving the use of allenes and vinylsilanes, respectively, as addends.
A stereocontrolled route to both enantiomers of the necine base dihydroxyheliotridane via intramolecular 1,3-dipolar addition using the same chiral precursor
Diastereofacialselectivity in an enantiospecific intramolecular 1,3-dipolar addition is controlled by adjusting the size of the tether between the dipole and the dipolarophile to give 2,3-disubstituted pyrrolidines enantiomeric with respect to the newly generated stereogenic 2,3-centres depending on the tether size; this leads to Stereocontrolledsynthesis of both enantiomers of the necine base d