Selective ring-rearrangement or ring-closing metathesis of bicyclo[3.2.1]octenes

Vicinal stereocenters via asymmetric allylic alkylation and Cope rearrangement: a straightforward route to functionally and stereochemically rich heterocycles

An asymmetric allylic alkylation/Cope rearrangement (AAA/[3,3]) capable of stereoselectively constructing vicinal stereocenters has been developed. Strategically integrated 4-methylation on the 3,3-dicyano-1,5-diene controls stereoselectivity and drives Cope rearrangement equilibrium in the forward direction. The AAA/[3,3] sequence rapidly converts abundant achiral and racemic starting materials into valuable (hetero)cycloalkane building blocks bearing significant functional and stereochemical complexity, highlighting the value of (hetero)cyclohexylidenemalononitriles as launching points for complex heterocycle synthesis. On this line, the resulting alkylidenemalononitrile moiety can be readily converted into amides via Hayashi-Lear amidation to ultimately yield amido-piperidines, tropanes, and related scaffolds with 3-5 stereocenters and drug-like functionality.

Heck Reaction Boosted Heterocycle Ring-Closing and Ring-Opening Rearrangement: A Strategy for the Synthesis of Indolyl-Type Ligands

A novel method for P-involved heterocycle ring-closing-ring-opening rearrangement (HRR) via the Heck reaction is disclosed. The approach enables direct installation of a phosphorus-containing aryl group onto the C2 position of indole. This new rearrangement directly transforms easily prepared indole derivatives into indolyl-derived phosphonates and phosphinic acids with high yields, and many of the products are difficult to obtain by using established methods. This new HRR reaction provides an extremely simple and step-economic method to induce C-C bond formation and P-N bond cleavage for the synthesis of a variety of indolyl-type ligands.

Unexpected metal-free synthesis of trifluoromethyl arenes via tandem coupling of dicyanoalkenes and conjugated fluorinated sulfinyl imines

A novel strategy for the synthesis of policyclic trifluoromethyl arenes has been devised. It involves a DBU-promoted tandem cycloaromatization reaction of dicyanoalkenes and fluorinated conjugated sulfinyl imines. This unprecedented transformation is a metal-free and air-tolerant process that takes place from readily available starting materials under mild reaction conditions.

[3,3] Ring Rearrangement of Oxo- or Aza-Bridged Bicyclo[3.2.1]octene-Based 1,5-Dienes

We report that oxo- or aza-bridged alkylidenemalononitrile-cycloheptenes undergo a [3,3] ring rearrangement to yield cyclopenta-fused dihydro-furans or pyrroles. Described herein are the origins of the serendipitous discovery, scope studies, and representative functional group interconversion chemistry.