A new practical 10 step synthesis of (1S,2R)-2-acetyl-1-methylcyclobutaneacetic acid 15 is reported, which has as a key step a rhodium catalyzed intramolecular carbenoid cyclization of the α-diazo-β-ketosulfone 5, readily available from (+)-citronellol 2. Since 15 has already been converted into (+)-grandisol 1, the major pheromone of the cotton boll-weevil Anthonomus grandis, the described preparation constitutes a new formal synthesis of the optically active pheromone.
Monteiro, H. J., & Zukerman-Schpector, J. (1996). A new practical synthesis of (+)-grandisol from (+)-citronellol using an intramolecular carbenoid cyclization. Tetrahedron, 52(11), 3879–3888. https://doi.org/10.1016/S0040-4020(96)00175-5