In this article, we describe our efforts on the total synthesis of bolivianine (1) and isobolivianine (2), involving the synthesis of onoseriolide (3). The first generation synthesis of bolivianine was completed in 21 steps by following a chiral resolution strategy. Based on the potential biogenetic relationship between bolivianine (1), onoseriolide (3), and β-(E)-ocimene (8), the second generation synthesis of bolivianine was biomimetically achieved from commercially available (+)-verbenone in 14 steps. The improved total synthesis features an unprecedented palladium-catalyzed intramolecular cyclopropanation through an allylic metal carbene, for the construction of the ABC tricyclic system, and a Diels–Alder/intramolecular hetero-Diels–Alder (DA/IMHDA) cascade for installation of the EFG tricyclic skeleton with the correct stereochemistry. Transformation from bolivianine to isobolivianine was facilitated in the presence of acid. The biosynthetic mechanism and the excellent regio- and endo selectivities in the cascade are well supported by theoretical chemistry based on the DFT calculations.

Curcuphenol is an interesting sesquiterpenoid with diverse bioactivities. Exploration of a concise and scalable synthetic route is still of significance in spite that many asymmetric total syntheses have been achieved. We report an expedient asymmetric synthesis of (R)-curcuphenol from citronellal, which features only two purification operations in the overall six-step synthesis.

A catalytic amount of Zeise's dimer and 15-crown-5 were combined to effectively promote the regioselective formation of β-alkoxy ketones from 2-(homopropargyloxy)ethanols in dimethoxyethane. The desired products were obtained in 59–98 % yields with up to 17:1 exo/endo regioselectivity. The methodology allows access to β-hydroxy ketones as an aldol reaction alternative.