Nothing left to chance: A convenient protocol for selective cross‐coupling of diazo compounds for the convergent synthesis of alkenes was developed (see scheme; EDG=aryl, heteroaryl, vinyl; R=O‐alkyl, aryl). The selectivity control elements were identified by ReactIR and DFT calculations and provide a framework for the design of viable diazo coupling reactions.
The synthesis of highly functionalized pyrroles has been achieved by reaction of rhodium-stabilized imino-carbenes with furans. The reaction features an initial [3+2] annulation to form bicyclic hemiaminals, followed by ring opening to generate trisubstituted pyrroles.
The tandem ylide-formation/[2,3]-sigmatropic rearrangement between donor/acceptor rhodium-carbenoids and chiral allyl alcohols is a convergent C—C bond forming process, which generates two vicinal stereogenic centers. Any of the four possible stereoisomers can be selectively synthesized by appropriate combination of the chiral catalyst Rh2(DOSP)4 and the chiral alcohol.
Take your pick… A practical method for the synthesis of structurally diverse rhodium vinylcarbenes from stable 1-sulfonyl-1,2,3-triazole precursors has been developed. The reaction is general for a broad range of 4-alkenyl triazoles and dienes, enabling the stereoselective synthesis of a variety of polycyclic imines, which are readily converted into amines or aldehydes in a one-pot process.
Alkaloids, secondary metabolites that contain basic nitrogen atoms, are some of the most well-known biologically active natural products in chemistry and medicine1. Although the efficient laboratory syntheses of alkaloids would enable researchers to study and optimize their biological properties,2 the basicity and nucleophilicity of nitrogen, its susceptibility to oxidation, and its ability to alter reaction outcomes in unexpected ways – for example, through stereochemical instability and neighboring group participation – complicates their preparation in the laboratory. Efforts to address these issues have led to the invention of a large number of protecting groups that temper the reactivity of nitrogen3; however, the use of protecting groups typically introduce additional steps and obstacles into the synthetic route. Alternatively, the use of aromatic nitrogen heterocycles as synthetic precursors can attenuate the reactivity of nitrogen and streamline synthetic strategies4. In this manuscript, we use such an approach to achieve a synthesis of the complex anti-HIV alkaloid (+)-batzelladine B in nine steps (longest-linear sequence) from simple pyrrole-based starting materials. The route employs several key transformations that would be challenging or impossible to implement using saturated nitrogen heterocycles and highlights some of the advantages conferred by the use of aromatic starting materials.
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