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Abstract Typical approaches to heterocycle construction require significant changes in synthetic strategy even for a change as minor as increasing the ring size. The ability to access multiple heterocyclic scaffolds through a common synthetic approach, simply through trivial modification of one reaction component, would enable facile access to diverse libraries of structural analogues of core scaffolds. Here, we show that urea‐derived ligands effectively promote Pd‐mediated chainwalking processes to enable remote heteroannulation for the rapid construction of six‐ and seven‐membered azaheterocycles under essentially identical reaction conditions. This method demonstrates good functional group tolerance and effectively engages sterically hindered substrates. In addition, this reaction is applicable to target‐oriented synthesis, demonstrated through the formal synthesis of antimalarial alkaloid galipinine.
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Stereoselective [4+2]‐Cycloaddition with Chiral Alkenylboranes
Abstract A method for the stereoselective [4+2]‐cycloaddition of alkenylboranes and dienes is presented. This transformation was accomplished through the introduction of a new strategy that involves the use of chiral N‐protonated alkenyl oxazaborolidines as dieneophiles. The reaction leads to the formation of products that can be readily derivatized to more complex structural motifs through stereospecific transformations of the C−B bond such as oxidation and homologation. Detailed computation evaluation of the reaction has uncovered a surprising role of the counterion on stereoselectivity.
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- PAR ID:
- 10149480
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Angewandte Chemie International Edition
- Volume:
- 59
- Issue:
- 28
- ISSN:
- 1433-7851
- Page Range / eLocation ID:
- p. 11432-11439
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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