High-Level Data Fusion Enables the Chemoinformatically Guided Discovery of Chiral Disulfonimide Catalysts for Atropselective Iodination of 2-Amino-6-arylpyridines.

The atropselective iodination of 2-amino-6-arylpyridines catalyzed by chiral disulfonimides (DSIs) is described. Key to the development of this transformation was the use of a chemoinformatically guided workflow for the curation of a structurally diverse training set of DSI catalysts. Utilization of this catalyst training set in the atropselective iodination across a variety 2-aminopyridine substrates allowed for the recommendation of statistically higher-performing DSIs for this reaction. Data Fusion techniques were implemented to successfully predict the performance of catalysts when classical linear regression analysis failed to provide suitable models. This effort identified a privileged class of 3,3'-alkynyl-DSI catalysts which were effective in catalyzing the iodination of a variety of 2-amino-6-arylpyridines with high stereoselectivity and generality. Subsequent preparative-scale demonstrations highlighted the utility of this reaction by providing iodinated pyridines >90:10 er and in good chemical yield.

Conformational effects and stereocontrol in synthesis studies of medium-ring dolabellane carbocycles.

Stereoselective reactions are described which lead to functionalization of the dolabellane skeleton. The stereoselectivity is attributed to conformational effects imposed by the eleven-membered ring. An efficient pathway provides for the stereocontrolled synthesis of nonracemic 6(S)-hydroxy-4(E)-dolabellene-3-one 12 and related derivatives.

General Methodology for the Preparation of Unsymmetrical α-Linked Bisenones via Ligandless Cross-Coupling Reactions.

A stereocontrolled Stille cross-coupling reaction, involving the use of Pd2dba3, provides a general procedure for the synthesis of unsymmetrical α-linked bisenone systems. The transformation is achieved in the absence of phosphine ligands under conditions that promote the stabilization of "ligandless" palladium catalysis. The extension of these studies illustrates Suzuki-Miyaura reactions of 2-boryl-2-cyclohexen-1-one with iodide and triflate partners for the synthesis of novel electron-deficient 1,3-dienes.

A Stereoselective Michael-Mannich Annelation Strategy for the Construction of Novel Tetrahydrocarbazoles.

A novel annelation strategy has been devised for stereoselective synthesis of tetrahydrocarbazoles. The pathway features a regio- and stereocontrolled condensation of indole and its substituted derivatives with electron-deficient 1,3-dienes via a Michael-Mannich reaction sequence. An extension of this method to include cross-conjugated allenes as substrates also results in a Michael-Mannich-Michael cascade, incorporating 2 equiv of indole with increasing product complexity. The formal 4π + 2π cyclization describes a concise route to polycyclic alkaloids of this family.

Stereocontrol in asymmetric S(E)' reactions of γ-substituted α,ß-unsaturated aldehydes.

Asymmetric SE' reactions of (E)- and (Z)-γ-substituted-α,ß-unsaturated aldehydes have been studied for the stereocontrolled preparation of nonracemic alcohols. Mild exchange reactions of allylic stannanes provide access to chiral 1,3-bis(tolylsulfonyl)-4,5-diphenyl-1,3-diaza-2-borolidines. These reagents display reactivity with the γ-substituted α,ß-unsaturated aldehydes, which is characterized by matched and mismatched elements of stereocontrol. Computational analysis (using density functional theory) provides valuable insights to guide reaction development.

Stereocontrolled synthesis of the tricyclic ABC ring system of daphnicyclidin A.

An enantiocontrolled synthesis pathway has been developed to provide formation of tricyclic amine 7, representing the ABC ring system of the complex alkaloid daphnicyclidin A (1). Our efforts describe preparation of the Z-hexahydro-(1H)-azocine 29 and cyclization to construct the novel 4-azabicyclo[5.3.2]dodecane 31. Transannular reductive amination following the deprotection of 31 gave the desired tertiary amine 7.