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A cascade three-component iodoazidation of para-quinone methides to construct spiro[4.5]deca-6,9-dien-8-ones under mild conditions has been developed. The chemoselective 1,6-addition of azide radical triggered a regioselective 5-exo-dig cyclization/radical coupling sequence, enabling C–N, C–C, and C–I bond formations in a one-pot procedure with high efficiency. [ABSTRACT FROM AUTHOR]

Facile, straightforward, and asymmetric total syntheses of (+)-chimonanthine (1), (+)-folicanthine (2), and (−)-calycanthine (3) were accomplished in four to five steps from commercially available tryptamine. The synthesis features copper-mediated asymmetric cyclodimerization of chiral tryptamine derivative, which established a new entry into constructing the sterically hindered vicinal quaternary stereogenic carbon centers of dimeric hexahydropyrroloindole alkaloids in one procedure. An unprecedented base-induced isomerization from the chimonanthine skeleton to the calycanthine skeleton was observed and facilitated the synthesis of (−)-calycanthine (3). [ABSTRACT FROM AUTHOR]