N-Hexadecanoylhomoserine lactone

N-acyl homoserine lactones are bacterial signalling molecules involved in regulating diverse metabolic functions, particularly those relating to virulence, in concert with cell density. Each aspect of the signalling pathway, from production and recognition of the signal to expression of the target genes, offers a potential opportunity for exploitation. Attention is now focusing on the development of novel methods for bacterial enumeration, modulation of bacterial virulence and flexible, coordinated expression of heterologous genes through the use of N-acyl-homoserine-lactone-based systems.

Covering: 2000-2018In this review, we highlight recent examples of natural product total syntheses employing transition metal-mediated/catalyzed carbonylative cyclization strategies to build key ring systems. It mainly covers carbonylative cyclizations for the construction of O-heterocycles, N-heterocycles and carbocycles including cyclic ketones and phenols. The reaction types include carbonylation of epoxide to β-lactones, carbonylative (macro)lactonization/lactamization, the Semmelhack reaction, tandem hydroformylation-cyclization, the Pauson-Khand reaction, carbonylative C-H activation cyclization, the Stille/Suzuki carbonylation, [n + m + 1] carbonylative cycloaddition, the Dötz annulation, and others.

Oxidation of C-B bonds is extensively used in organic synthesis, materials science, and chemically biology. However, these oxidations are usually limited to the oxidation of C(sp3)-B and C(sp2)-B bonds. The C(sp)-B bond oxidation is rarely developed. Herein we present a novel strategy for the preparation of γ-lactones via the oxidation of enynyl boronates. This process successively involves the C(sp)-B bond oxidation, the epoxidation of C-C double bond and the lactonization. This protocol provided various γ-lactones and unsaturated butenolides efficiently that are prevalent in numerous nature products and bioactive molecules. Most importantly, asymmetric oxidative lactonization of enynyl boronates was also achieved, providing chiral γ-lactones in high enantioselectivities and diastereoselectivities. The versatile transformations and ubiquity of γ-lactones shed light on the importance of this strategy in the construction and late-stage functionalization of complex molecules.