Bicyclic unsaturated diols undergo a path selective modular domino transformation upon subjection to Pb(OAc)4, the reaction being biased to the nature of the angular substituent. The magnitude of the linking chain and the nature of the angular substituent determine the reaction course. Methylene ether linkage acts as an autoremovable directing group (ring-retained domino product 5), whereas a propylene linkage switches the path toward the ring-expanded type 21 domino product. Reaction times were substantially reduced using microwave irradiation.
Structurally different products can be reached selectively from unsaturated vicinal bicyclic diols, which differ only by the epoxide configuration at the angular position. It is possible to modify the regiochemical outcome of the domino process in such a way as to create a different pathway, [4 + 2] versus [4 + 3 + 2], and control product distribution by using the configuration bias. No previous example of a domino variant of the [4 + 3 + 2] process appears to have been documented.
Keywords: Epoxidation / Domino reactions / Lactones / Terpenoids / Fused-ring systemsThe methodology described in this paper involves the epoxidation of cyclic ene-acetals to spontaneously generate 6α-hydroxy-bis-acetals that could serve as precursors for a Cannizzaro-type rearrangement, yielding bis-angularly substituted cis-fused lactones. Both the oxidizing reagent, m-CPBA
A Pb(OAc) 4 -mediated, path selective, modular domino transformation using an octaline diol framework as a probe is described. Alteration of the nature of the angular substituent or the length of the tether chain controls the effectiveness of the "ring-expanded" versus "ring-retained" domino path. The solvent can modify the behaviour of the transient intermediates and the reaction time is reduced under microwave heating, whereas water cleanly promotes oxidative/pericyclic
Carbinol-tethered octalin-diols (1), which differ only by the C11 configuration at the angular position, were transformed selectively to three types of structurally unrelated original scaffolds such as unsymmetrical octahydroanthracenes (5/7), furofuranes (6), or spirans (8/9) via a two-step protocol. The 11S* configuration ensures a C13-C4 Friedel-Crafts type C-C bonding (through an unprecedented oxidative cleavage-triggered domino process) while the 11R* configuration allows for a C13-C2 Marson-type Friedel-Crafts C-C bonding (through a nucleophilic acetal opening).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.