Synthesis and rhodium complexation of enantiomerically enriched bicyclo[3.3.1]nona-2,6-diene

Enantiomerically enriched (S,S)-bicyclo[3.3.1]nona-2,6-diene has been synthesised from the readily available diketone (S,S)-bicyclo[3.3.1]nonane-2,6-dione. The stereochemical purity is maintained on complexation to rhodium. There is a very strong preference for the formation of the homochiral over the heterochiral (alkene)2Rh+ OTf− complex; the self-recognition involved can be rationalised by analysis of DFT calculations.

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(2S,6S)-Bicyclo[3.3.1]nonane-2,6-dioneC9H12O2[α]D21=+176.6 (c 0.5, CHCl3)Source of chirality: yeast kinetic resolutionAbsolute configuration: (2S,6S)

(2S,6S)-Bicyclo[3.3.1]nona-2,6-dieneC9H12[α]D21=-121 (c 0.89, CHCl3)Source of chirality: enantiomerically pure ketone precursorAbsolute configuration: (2S,6S)

((2S,6S)-Bicyclo[3.3.1]nona-2,6-diene)2′,4′-pentanedionato rhodiumC14H19O2Rh[α]D21=-73 (c 0.51, CHCl3)Source of chirality: enantiomerically pure diene precursorAbsolute configuration: (2S,6S) (diene chirality)

(Bis-(S,S)-bicyclo[3.3.1]nona-2,6-diene)rhodium trifluoromethanesulfonateC19H24F3O3SRh[α]D21=-217 (c 0.29, CHCl3)Source of chirality: enantiomerically pure diene precursorAbsolute configuration: (2S,6S) (diene chirality)

(Bis-(S,S)-bicyclo[3.3.1]nona-2,6-diene)rhodium trifluoromethanesulfonateC18H24Cl2Rh2[α]D21=-260 (c 0.23, CHCl3)Source of chirality: enantiomerically pure diene precursorAbsolute configuration: (2S,6S) (diene chirality)