RESUMO
The collaborative total synthesis of darobactin A, a recently isolated antibiotic that selectively targets Gram-negative bacteria, has been accomplished in a convergent fashion with a longest linear sequence of 16 steps from d-Garner's aldehyde and l-serine. Scalable routes toward three non-canonical amino acids were developed to enable the synthesis. The closure of the bismacrocycle was realized through sequential, halogen-selective Larock indole syntheses, where the proper order of cyclizations proved crucial for the formation of the desired atropisomer of the natural product.
Assuntos
Aldeídos , Aminoácidos , Aldeídos/química , Aminoácidos/química , Ciclização , Fenilpropionatos , EstereoisomerismoRESUMO
The direct and chemoselective 3'-phosphoramidation, phosphorylation and acylation of nucleosides are described. Upon the discovery of a novel 3'-phosphorylamidation of therapeutic nucleoside analogues with DBU, we explored the mechanism of this rare selectivity through a combination of NMR spectroscopy and computational studies. The NMR and computational findings allowed us to develop a predictive computational model that accurately assesses the potential for 3'-functionalization for a broad range of nucleosides and nucleoside mimetics. The synthetic utility of this model was exemplified by demonstration on a broad scope of nucleosides and electrophiles yielding targets that were previously only accessible via a protection/deprotection sequence or an enzymatic approach.
RESUMO
1,1-Disubstituted aryl cyclopropyl nitriles are useful moieties in biologically active compounds and provide access to a range of cyclopropyl derivatives. Herein, we describe the development of a palladium-catalyzed α-arylation of cyclopropyl, cyclobutyl, and cyclopentyl nitriles that affords these functional groups in one step from a variety of aryl bromides in good to excellent yields. Furthermore, we demonstrate the transformation of aryl cyclopropyl nitriles into aryl trifluoromethyl cyclopropanes.