The Nozaki-Hiyama-Takai-Kishi (NHTK) reaction was discovered in the late 1970s and, since then, its main application has been its use in total synthesis. In this comprehensive review, the efficiency of the NHKT reaction in the synthesis of a great number of different scaffolds present in complex natural products is analyzed. The preparation of enol and allylic and propargylic alcohol motifs is discussed, highlighting factors such as yield, chemoselectivity, stereoselectivity, or the importance of protecting groups. The review is divided into two main sections: intermolecular and intramolecular NHTK reactions. A final discussion about the current "state-of-art" and future perspectives for the use of this transformation in total synthesis is also included.
New cytotoxic polyketide macrolides named phormidolides B and C were isolated from a marine sponge of the Petrosiidae family collected off the coast of Pemba (Tanzania). The isolation, structure elucidation, and enantioselective synthesis of three diastereomers of the macrocyclic core is described herein. The described synthetic methodology started from 2-deoxy-D-ribose or 2-deoxy-L-ribose and afforded the desired macrocycles with high enantiomeric purity. The key step of the synthesis is the formation of the Z-trisubstituted double bond using a Julia-Kocienski olefination. The versatility of the synthetic methodology may provide access to other enantiopure macrocycles by making changes in the starting materials or chiral inductors.
The first enantioselective synthesis of the polyhydroxylated chain common to marine natural products oscillariolide and phormidolides A-C is described herein. This chain represents a synthetic challenge that needs to be solved before the total synthesis of this family of natural products can be approached. It contains seven stereocenters, six of them having a syn-hydroxylated functionality, and a tricky terminal (E)-bromomethoxydiene (BMD). The described effective enantioselective strategy affords the polyketide chain and represents an important breakthrough to complete the total synthesis of these marine compounds.
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