A Concise Formal Total Synthesis of (±)-Laurokamurene B and (±)-β-Cuparenone

The study describes a concise four-step formal total synthesis of racemic (+/-)-laurokamurene B, a sesquiterpene with a rearranged laurene carbon framework. This method also extends to the formal total synthesis of beta-cuparenone. Compared with previously reported laurokamurene B's syntheses, our approach significantly reduces the total number of reaction steps by leveraging the known scaffolds as the key concept. Optimized esterification for the generation of appropriately substituted cinnamate esters, one-pot polyphosphoric acid (PPA) mediated fragmentation followed by Friedel-Crafts acylation, and intramolecular cyclization led to the efficient construction of pivotal intermediate 3-arylcyclopent-2-en-1-one with a quaternary center; subsequent alpha-methylation and reductive deoxygenation resulted into the marine natural product (+/-)-laurokamurene B. Additionally, beta-methylation and deoxygenation of the obtained key 3-arylcyclopente-2-en-1-one intermediate could also serve for the formal total synthesis of (+/-)-beta-cuparenone in the shortest approach.