Design, synthesis, and diversification of 3,5-substituted enone library

Total synthesis of (+)-ar-macrocarpene

This report features the first catalytic asymmetric total synthesis of a sesquiterpene, (+)-ar-macrocarpene (1), in 7 steps with 42.1% overall yields from commercially available inexpensive 5,5-dimethylcyclohexane 1,3-dione. This strategy relies on a key [3,3]-sigmatropic rearrangement effecting reductive transposition through allylic diazene rearrangement (ADR) in a single step from intermediate allylic alcohol (+)-12 under the Mitsunobu reaction conditions with o-nitrobenzenesulfonyl hydrazide (o-NBSH). Enantioselective reduction of α-bromo vinylogous ester 16 under the Corey-Bakshi-Shibata reduction conditions forges the required stereocenter in the allylic alcohol (+)-12 in a highly enantioenriched manner (95% ee).

Synthesis of β-Substituted Cyclic Enones via Phosphonium Salt-Activated, Palladium-Catalyzed Cross-Coupling of Cyclic 1,3-Diones

Phosphonium salt-activated, Pd-catalyzed Suzuki-Miyaura and Sonogashira cross-coupling reactions of cyclic 1,3-diones in the synthesis of β-substituted cyclic enones are described. These transformations exhibit good isolated yield and high generality with respect to both substrates and coupling partners. Extension of the substrate scope to cyclic 1,3-dione equivalents, such as 2-cyanocyclohexanone (4), is also briefly examined.

Synthesis of a 2(1H)-pyridone library via rhodium-catalyzed formation of isomunchones

Through the use of the dipolar cycloaddition of isomunchones with olefins the 2(1H)-pyridone ring system has been synthesized. (1) The use of different cyclization partners followed by diversification of the initial scaffold has provided libraries of 4-hydroxy-2(1H)-pyridones. There are no examples of this ring system in either PubChem or the MLSMR.