Significance In a quest for antibiotics that may display durable clinical lifetimes, analogs of the glycopeptide antibiotics, including vancomycin, have been designed that not only directly overcome the molecular basis of existing vancomycin resistance but also contain two added peripheral modifications that endow them with two additional independent mechanisms of actions not found in the parent antibiotics. It is shown that such peripherally and binding pocket-modified vancomycin analogs display little propensity for acquired resistance by vancomycin-resistant Enterococci and that both their antimicrobial potency and durability against such challenges follow trends (three > two > one mechanisms of action) that are now predictable.

A review of efforts that have provided total syntheses of vancomycin and related glycopeptide antibiotics, their agylcons, and key analogues is provided. It is a tribute to developments in organic chemistry and the field of organic synthesis that not only can molecules of this complexity be prepared today by total synthesis, but that such efforts can be extended to the preparation of previously inaccessible key analogues that contain deep-seated structural changes. With the increasing prevalence of acquired bacterial resistance to existing classes of antibiotics and with the emergence of vancomycin resistant pathogens (VRSA and VRE), the studies pave the way for the examination of synthetic analogues rationally designed to not only overcome vancomycin resistance, but to provide the foundation for the development of even more powerful and durable antibiotics.

Process Mass Intensity (PMI) for (a) process in organic solvents, (b) process in water with surfactants.

Transition-metal-catalyzed carbon–carbon and carbon–heteroatom bond formations are among the most heavily used types of reactions in both academic and industrial settings. As important as these are to the synthetic community, such cross-couplings come with a heavy price to our environment, and sustainability. E Factors are one measure of waste created, and organic solvents, by far, are the main contributors to the high values associated, in particular, with the pharmaceutical and fine-chemical companies which utilize these reactions. An alternative to organic solvents in which cross-couplings are run can be found in the form of micellar catalysis, wherein nanoparticles composed of newly introduced designer surfactants enable the same cross-couplings, albeit in water, with most taking place at room temperature. In the absence of an organic solvent as the reaction medium, organic waste and hence, E Factors, drop dramatically.

The reduction of ketones with pinacolborane (4,4,5,5-tetramethyl-1,3,2-dioxaborolane) is catalyzed by 5 mol % NaOt-Bu at ambient temperature. The reaction is high yielding and general, providing complete conversion of aryl and dialkyl ketones. Although spectroscopic studies of the active hydride source in benzene-d(6) were complicated due to poor solubility, the data are consistent with the active hydride source being the trialkoxyborohydride, which is believed to be present in low concentration under the reaction conditions. Performing analogous studies in tetrahydrofuran resulted in a complex equilibrium between several different boron-containing species in which the trialkoxyborohydride compound was the major species.