1.1: n-butyllithium / tetrahydrofuran; hexane / -78 °C / Inert atmosphere; Cooling with acetone-dry ice 1.2: -78 - 4 °C / Inert atmosphere 2.1: tris-(dibenzylideneacetone)dipalladium(0); [(R)-methoxy(furyl)BIPHEP]; cesium fluoride / tetrahydrofuran; water / 12 h / 60 °C / Inert atmosphere 3.1: ozone / dichloromethane / -78 °C 3.2: 20 °C / Inert atmosphere 4.1: potassium hydroxide / tetrahydrofuran; ethanol / 1 h / Inert atmosphere View Scheme

1: Al(OiPr)3 2: (i) polyphosphoric acid, (ii) sulfur View Scheme

aluminum isopropoxide

1: Al(OiPr)3 2: (i) polyphosphoric acid, (ii) sulfur 3: KMnO4 View Scheme