A stereoselective construction of a bicyclo[m.n.1] ring system from enol-lactones

Domino reactions for the synthesis of bridged bicyclic frameworks: fast access to bicyclo[n.3.1]alkanes

“…Compounds 3 were isolated together with their products of reduction at the ketone carbonyl. 17 A successful approach to the synthesis of the bicyclo[3.3.1]nonan-9-one core of hyperforin (compound 4) developed by Mehta and Bera was based on this strategy (Scheme 3). Thus, chemoselective DIBAL-H reduction of the lactone moiety in starting material 1, already containing one of the quaternary stereocenters of the natural product, furnished a lactol that, after ring opening to the corresponding hydroxyaldehyde and subsequent ring closing via an aldol reaction, afforded the desired bicyclo[3.3.1]nonan-9-one scaffold.…”

Stereocontrolled Synthesis and Reactions of Bicyclo[3.3.1]nonanes

“…28 The conversion of the enollactones with diisobutylaluminum hydride (DIBAL-H) gave exo,syn-bicyclononane-2,9-diols as sole products in high yields. The stereoselectivity of the reaction is accounted for by the six-membered chair-like transition state.…”

“…A stereoselective transformation of enol-lactones 27 through the aldehyde-enolate derivatives resulted in formation of bicyclo[3.3.1] nonanediols with a defined configuration (Scheme 18). 28 The conversion of the enollactones with diisobutylaluminum hydride (DIBAL-H) gave exo,syn-bicyclononane-2,9-diols as sole products in high yields. The stereoselectivity of the reaction is accounted for by the six-membered chair-like transition state.…”

Rearrangements of α-Diazo-β-hydroxyketones for the Synthesis of Bicyclo[m.n.1]alkanones

“…There are not many examples of a single strategy or reaction type that has been demonstrated to furnish a range of functionalized bicyclo­[ m . n .1]­octane, -nonane, and -decane systems in good yields and selectivities . Herein we describe such a strategy via the synthesis and rearrangements of α-diazo-β-hydroxyalkanones, which not only generates an array of bridged bicyclic compounds but also provides such products endowed with functional groups for further manipulations.…”