Stereoselective Synthesis of Kalafungin Based on CuI‐Catalyzed Tandem Reactions of Arylethynes Containing an Ortho‐(1‐Hydroxyethyl) Substituent with Alkyl Diazoacetates

An isochromene synthesis is developed utilizing a cascade reaction involving a CuI catalyzed coupling reaction between an alkyne and diazoacetate followed by allenoate isomerization and subsequent oxa‐Michael addition. The cascade sequence was also demonstrated for the synthesis of naphthalenes. Furthermore, the methodology developed herein was applied toward a stereoselective synthesis of pyranonaphthoquinone kalafungin.