Synthesis of the Fully Functionalized Bicyclic Core of Garsubellin A

N-Phenylselenophthalimide

“…35 In a reaction reminiscent of eq 14, the cyclization of an unsaturated enol acetate was effected with NPSP in the presence of tin tetrachloride (eq 24). 36 The cyclization of tryptophan derivatives to the corresponding pyrroloindoles was reported simultaneously by two groups. 37 An example is shown in eq 25.…”

Stereocontrolled Synthesis and Reactions of Bicyclo[3.3.1]nonanes

“…This makes the core skeleton of a natural product garsubellin, which has neurotropic properties and is a potential candidate for the treatment of neurodegenerative diseases. 23 reduced to dihydroxy-ester, which after hydrolysis of the ethyl ester group, followed by treatment with DCC, 4-DMAP and subsequent oxidation provided lactone 20. Introduction of the requisite b-keto ester moiety was accomplished by acylation of the enolate, generated from 20, with methyl cyanoformate (Scheme 14).…”

Synthetic efforts toward [3.3.1] bridged bicyclic phloroglucinol natural products

“…The C4-C5 bond has been formed using a [3+2] cycloaddition as well as successful palladium mediated, aldol and pinacol cyclization strategies. The C5-C6 bond selenocyclization disconnection by Nicolaou 6 was the first reported strategy toward this natural product class. A number of other researchers have also chosen to tackle this same bond to close the core.…”

“…6 He selected garsubellin A ( 2 ) as his primary target (Scheme 3) with the expectation that the final synthetic route could later be slightly modified to access other similar target structures. Nicolaou’s route centered on rapidly assembling the [3.3.1]-core by forming the C5-C6 bond employing an intramolecular union between a prenyl group and β-keto ester moiety.…”