Synthetic Studies of Sesquiterpenes with the Dunniane Skeleton

Abstract

The first synthetic approach to the entire carbon skeleton of the sesquiterpenes dunniane and cumacrene has been developed. The sequence features a [2+2] photochemical reaction of a chiral 2(5H)-furanone with ethylene to form the cyclobutane, a Meyer-Schuster-type rearrangement of an α-acety-

Recent Developments in the Meyer‐Schuster Rearrangement

“…During synthetic studies towards sesquiterpenes with the dunniane skeleton, the MSR proved to be fruitful (Scheme 55). [111] The advanced cyclobutane intermediate 224 reacted with ethynyl magnesium chloride to give the propargylic alcohols 225 in excellent yield. Then, MSR reaction performed with tris(triphenylsilyl)vanadate 34 a in toluene at 120 °C, and under microwave irradiation, gave the enal 226 which was used directly for the next steps including the synthesis of a dienamine followed by a Diels‐Alder reaction.…”

Acetylene and Ethylene: Universal C2 Molecular Units in Cycloaddition Reactions

“…series of sesquiterpenes with the dunniane skeleton; 93 oleander scale [Aspidiotus nerii (Bouche)] sex pheromone. 94 Cis-cyclobutane γ-amino acids in enantiomerically pure form can also be synthesized using ethylene cycloaddition as a key step (Scheme 29).…”

“…Numerous uracil derivatives 91 were successfully used in this reaction with the formation of cyclobutane derivatives and mixtures of the corresponding isomers. Interestingly, a cyclobutane fragment can regularly be found in biologically active compounds; thus, the strategy of [2+2] cycloaddition was successfully used in the synthesis of compounds such as heliannuol D, 92 a series of sesquiterpenes with the dunniane skeleton; 93 and oleander scale [ Aspidiotus nerii (Bouche)] sex pheromone. 94…”

Synthesis of Substituted β‐Functionalised Styrenes by Microwave‐Assisted Olefin Cross‐Metathesis and Scalable Synthesis of Apremilast

“…Importantly, the CM reaction of vinyl sulfones became useful also in medicinal chemistry context, as the α,β‐unsaturated sulfone function can increase the biological activity of a drug, therefore being sometimes referred as a “warhead” . Importantly, all published examples of vinyl sulfone cross‐metathesis are limited to rather reactive terminal alkene partners . Interestingly, functionalised styrenes ( 1 ), known in general as challenging substrates in olefin metathesis, according to our knowledge have never been tested in cross‐metathesis with vinyl sulfones ( 2 ) (Scheme c).…”