A Flexible Strategy for the Synthesis of Tri‐ and Tetracyclic Lupin Alkaloids: Synthesis of (+)‐Cytisine, (±)‐Anagyrine, and (±)‐Thermopsine

Looping the lupin: A general synthetic strategy for the construction of the lupin alkaloids has been defined and involves sequential formation of the N1C10 and C6C7 bonds, which are common to compounds of this class of natural products. The generality of the approach is exemplified by the syntheses of (+)-cytisine, (±)-anagyrine, and (±)-thermopsine (see scheme).