Catalytic Macrocyclization Strategies Using Continuous Flow: Formal Total Synthesis of Ivorenolide A.

A formal total synthesis of ivorenolide A has been accomplished employing a Z-selective olefin cross metathesis and a macrocyclic Glaser-Hay coupling as key steps. The macrocyclization protocol employed a phase separation/continuous flow manifold whose advantages include catalysis, fast reaction times, high concentrations, and facile scale-up.

Direct synthesis of macrodiolides via hafnium(IV) catalysis.

Efficient direct synthesis of macrodiolides via catalysis using Hf(OTf)4 is possible in high yields, forming water as the sole by-product. The first protocol for the direct synthesis of macrodiolides from equimolar mixtures of diols and dicarboxylic acids was developed (58-96%). In addition, modification of the reaction concentration allows for the synthesis of head-to-tail macrodiolides from the corresponding seco acids. The catalytic preparation of the macrodiolides using a commercially available catalyst without the need for slow addition or azeotropic condition provides an operationally simple alternative to protocols which employ toxic tin catalysts or stoichiometric activation strategies.

Heterocoupling of 2-naphthols enabled by a copper-N-heterocyclic carbene complex.

The reactivity of a Cu catalyst for oxidative coupling is modulated by a small molecule additive, diethyl malonate, that slows over-oxidation of 2-naphthols. Efficient heterocoupling between electron-rich and electron-poor 2-naphthols/2-naphthylamines affords C(1)-symmetric BINOLs with yields ranging from 35-98%.