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It is a challenging objective in synthetic organic chemistry to create efficient access to biologically active compounds. In particular, one structural element which is frequently incorporated into the framework of complex natural products is a β-hydroxy ketone. In this context, the aldol reaction is the most important transformation to generate this structural element as it not only creates new C–C bonds but also establishes stereogenic centers. In recent years, a large variety of highly selective methodologies of aldol and aldol-type reactions have been put forward. In this regard, the vinylogous Mukaiyama aldol reaction (VMAR) became a pivotal transformation as it allows the synthesis of larger fragments while incorporating 1,5-relationships and generating two new stereocenters and one double bond simultaneously. This review summarizes and updates methodology-oriented and target-oriented research focused on the various aspects of the vinylogous Mukaiyama aldol (VMA) reaction. This manuscript comprehensively condenses the last four years of research, covering the period 2016–2019.

International audience; Polyketides are a fascinating class of natural products with highly diverse, often complex structures combined with a likewise impressive breath of strong and selective biological activities. This chapter discusses the logic of biosynthetic polyketide assembly. It focuses on the introduction of the basic mechanisms and concepts of polyketide core structure assembly using a number of well-studied representative examples, thus allowing to compare the biosynthetic versus chemical synthetic strategies to assemble such beautiful small molecules. Despite the structural diversity of polyketide natural products, there are only few different catalytic domains facilitating a small number of basic reactions common to all types of PKSs that are crucial for product biosynthesis. The structural and functional space covered by bioactive small molecules is further expanded by post-PKS functionalization reactions catalyzed by so-called tailoring enzymes. This includes reorganization of the entire PKS core but also subtle changes by group transfer reactions or oxidative transformations.