Scheme 3.

Substrate-controlled IMDA syntheses: (a) Opatz’s total synthesis of (−)-hymenosetin (4);²⁸ (b) Williams’ total synthesis of (+)-apiosporamide (5);³⁰ (c) Tadano’s total synthesis of (+)-tubelactomicin A (12);^32,33 (d) Kalesse’s total synthesis of (−)-chlorotonil A (13).³⁵