Improved synthesis of (R)-7-hydroxycarvone from (S)-α-pinene

Recent advances in the syntheses of guaianolides

“…A three-step conversion of (−)-α-pinene 39 led to alcohol 40 . 20 Then, enone epoxidation and opening gave halohydrin that was orthogonally converted into mesylate 41 . This underwent a smooth stereoselective Favorskii rearrangement and conversion of hydroxy into bromide to give 42 .…”